Sutureless anastomosis systems

ABSTRACT

Anastomosis systems include fittings and compression mechanisms for effecting end-end or end-side couplings of biological or synthetic bypass grafts to vessel locations. The fittings are tubular and surround end regions of the graft. In some applications an end region of the graft is everted and surrounds an exterior of the fitting, in which case the preferred compression mechanism is a retaining ring. A tool is used to evert the graft end region. In other applications, the fitting has an interior groove that receives an expandable retaining ring that urges the graft end region radially outwardly against the fitting. A graft deploying and securing system includes a needle for puncturing vessel tissue, a dilator, and a sheath adapted for containing a graft/fitting combination and guiding the combination into the vessel through an opening formed by the needle and dilator.

[0001] This application claims the benefit of Provisional ApplicationNo. 60/088,705 entitled “Bypass Graft Mechanical Securing Systems” filedJun. 10, 1998, and Provisional Application No. 60/111,948 entitled“Bypass Graft Positioning and Securing Systems” filed Dec. 11, 1998.

BACKGROUND OF THE INVENTION

[0002] This invention relates to devices for deploying and securing theends of bypass grafts designed to provide a fluid flow passage betweenat least two host vessel regions (or other tubular structure regions).More particularly, the invention relates to bypass grafts that aresecured at target host vessel locations thereby producing a fluid flowpassage from the first host vessel location through the bypass graft andto the second host vessel location. The bypass grafts and deploymentsystems of the invention do not require stopping or re-routing bloodflow to perform an anastomosis between a bypass graft and a host vessel.Accordingly, this invention describes sutureless anastomosis systemsthat do not require cardiopulmonary bypass support when treatingcoronary artery disease.

[0003] Current techniques for producing anastomoses during coronaryartery bypass grafting procedures involve placing the patient oncardiopulmonary bypass support, arresting the heart, and interruptingblood flow to suture, clip, or staple a bypass graft to the coronaryartery and aorta; cardiopulmonary bypass support is associated withsubstantial morbidity and mortality. The embodiments of the inventionposition and secure bypass grafts at host vessel locations withouthaving to stop or re-route blood flow. Accordingly, the embodiments ofthe invention do not require cardiopulmonary bypass support andarresting the heart while producing anastomoses to the coronaryarteries. In addition, the embodiments of the invention mitigate risksassociated with suturing, clipping, or stapling the bypass graft to thehost vessel(s), namely bleeding at the attachment sites and collapsingof the vessel around the incision point.

[0004] The invention addresses vascular bypass graft treatment regimensrequiring end-end anastomoses and end-side anastomoses to attach bypassgrafts to host vessels. The scope of the invention includes systems toposition and secure bypass grafts used to treat vascular diseases suchas atherosclerosis, arteriosclerosis, fistulas, aneurysms, occlusions,and thromboses. In addition, the systems may be used to bypass stentedvessel regions that have restenosed or thrombosed. The bypass grafts anddelivery systems of the invention are also used to attach the ends ofligated vessels, replace vessels harvested for bypass graftingprocedures (e.g. radial artery), and re-establish blood flow tobranching vessels which would otherwise be occluded during surgicalgrafting procedures (e.g. the renal arteries during abdominal aorticaneurysm treatment). In addition, the invention addresses otherapplications such as, but not limited to, producing arterial to venousshunts for hemodialysis patients, bypassing lesions and scar tissuelocated in the fallopian tubes causing infertility, attaching the ureterto the kidneys during transplants, and bypassing gastrointestinaldefects (occlusions, ulcers).

DESCRIPTION OF THE RELATED ART

[0005] Stenosed blood vessels cause ischemia potentially leading totissue infarction. Conventional techniques to treat partially orcompletely occluded vessels include balloon angioplasty, stentdeployment, atherectomy, and bypass grafting.

[0006] Coronary artery bypass grafting (CABG) procedures to treatcoronary artery disease have traditionally been performed through athoracotomy with the patient placed on cardiopulmonary bypass supportand using cardioplegia to induce cardiac arrest. Cardiac protection isrequired when performing bypass grafting procedures having prolongedischemia times. Current bypass grafting procedures involve interruptingblood flow to suture or staple the bypass graft to the host vessel walland create the anastomoses. When suturing, clipping, or stapling thebypass graft to the host vessel wall, a large incision is made throughthe host vessel and the bypass graft is sewn to the host vessel wallsuch that the endothelial layers of the bypass graft and vessel faceeach other. Bypass graft intima to host vessel intima apposition reducesthe incidence of thrombosis associated with biological reactions thatresult from blood contacting the epithelial layer of a harvested bypassgraft. This is especially relevant when using harvested vessels thathave a small inner diameter (e.g. (2 mm).

[0007] Less invasive attempts for positioning bypass grafts at targetvessel locations have used small ports to access the anatomy. Theseapproaches use endoscopic visualization and modified surgicalinstruments (e.g. clamps, scissors, scalpels, etc.) to position andsuture the ends of the bypass graft at the host vessel locations.Attempts to eliminate the need for cardiopulmonary bypass support whileperforming CABG procedures have benefited from devices that stabilizethe motion of the heart, retractors that temporarily occlude blood flowthrough the host vessel, and shunts that re-route the blood flow aroundthe anastomosis site. Stabilizers and retractors still requiresignificant time and complexity to expose the host vessel and suture thebypass graft to the host vessel wall. Shunts not only add to thecomplexity and length of the procedure, but they require a secondaryprocedure to close the insertion sites proximal and distal to theanastomosis site.

[0008] Attempts to automate formation of sutureless anastomoses have ledto mechanical stapling devices. Mechanical stapling devices have beenproposed for creating end-end anastomoses between the open ends oftransected vessels. Berggren, et al propose an automatic stapling devicefor use in microsurgery (U.S. Pat. Nos. 4,607,637; 4,624,257; 4,917,090;4,917,091). This stapling device has mating sections containing pinsthat are locked together after the vessel ends are fed through lumens inthe sections and everted over the pins. This stapling device maintainsintima to intima apposition for the severed vessel ends but has a largeprofile and requires impaling the everted vessel wall with the pins.Sakura describes a mechanical end-end stapling device designed toreattach severed vessels (U.S. Pat. No. 4,214,587). This device has awire wound into a zig-zag pattern to permit radial motion and containspins bonded to the wire that are used to penetrate tissue. One vesselend is everted over and secured to the pins of the end-end staplingdevice, and the other vessel end is advanced over the end-end staplingdevice and attached with the pins. Sauer, et al proposes anothermechanical end-end device that inserts mating pieces into each open endof a severed vessel (U.S. Pat. No. 5,503,635). Once positioned, themating pieces snap together thereby bonding the vessel ends. Theseend-end devices are amenable to reattaching severed vessels but are notsuitable to producing end-end anastomoses between a bypass graft and anintact vessel, especially when exposure to the vessel is limited.

[0009] Mechanical stapling devices have also been proposed for end-sideanastomoses. These devices are designed to insert bypass grafts,attached to the mechanical devices, into the host vessel through a largeincision and secure the bypass graft to the host vessel. Kasterdescribes vascular stapling apparatus for producing end-side anastomoses(U.S. Pat. Nos. 4,366,819; 4,368,736; and 5,234,447). Kaster's end-sideapparatus is inserted through a large incision in the host vessel wall.The apparatus has an inner flange that is placed against the interior ofthe vessel wall, and a locking ring that is affixed to the fitting andcontains spikes that penetrate into the vessel thereby securing theapparatus to the vessel wall. The bypass graft is itself secured to theapparatus in the everted or non-everted position through the use ofspikes incorporated in the apparatus design.

[0010] U.S. Surgical has developed automatic clip appliers that replacesuture stitches with clips (U.S. Pat. Nos. 5,868,761; 5,868,759;5,779,718). These clipping devices have been demonstrated to reduce thetime required when producing the anastomosis but still involve making alarge incision through the host vessel wall. As a result, blood flowthrough the host vessel must be interrupted while creating theanastomoses.

[0011] Gifford, et al provides end-side stapling devices (U.S. Pat. No.5,695,504) that secure harvested vessels to host vessel wallsmaintaining intima to intima apposition. This stapling device is alsoinserted through a large incision in the host vessel wall and usesstaples incorporated in the device to penetrate into tissue and securethe bypass graft to the host vessel.

[0012] Walsh, et al propose a similar end-side stapling device (U.S.Pat. Nos. 4,657,019; 4,787,386; 4,917,087). This end-side device has aring with tissue piercing pins. The bypass graft is everted over thering; then, the pins penetrate the bypass graft thereby securing thebypass graft to the ring. The ring is inserted through a large incisioncreated in the host vessel wall and the tissue piercing pins are used topuncture the host vessel wall. A clip is then used to preventdislodgment of the ring relative to the host vessel.

[0013] The end-side stapling devices previously described requireinsertion through a large incision, which dictates that blood flowthrough the host vessel must be interrupted during the process. Eventhough these and other clipping and stapling end-side anastomoticdevices have been designed to decrease the time required to create theanastomosis, interruption of blood flow through the host vesselincreases the morbidity and mortality of bypass grafting procedures,especially during beating heart CABG procedures. A recent experimentalstudy of the U.S. Surgical One-Shot anastomotic clip applier observedabrupt ventricular fibrillation during four of fourteen internalthoracic artery to left anterior descending artery anastomoses in partdue to coronary occlusion times exceeding 90 seconds (Heijmen, et al. Anovel one-shot anastomotic stapler prototype for coronary bypassgrafting on the beating heart: feasibility in the pig. J ThoracCardiovasc Surg. 117:117-25; 1999).

[0014] A need thus exists for bypass grafts and delivery systems thatare capable of quickly producing an anastomosis between a bypass graftand a host vessel wall without having to stop or re-route blood flow.These anastomoses must withstand the pressure exerted by the pumpingheart and ensure blood does not leak from the anastomoses into thethoracic cavity, abdominal cavity, or other region exterior to thevessel wall.

SUMMARY OF THE INVENTION

[0015] The embodiments of the present invention provide suturelessanastomosis systems that enable a physician to quickly and accuratelysecure a bypass graft to a host vessel or other tubular body structure.In addition, the invention enables the physician to ensure bypass graftstability, and prevent leaking at the vessel attachment points. Thedelivery systems of the invention do not require stopping or re-routingblood flow while producing the anastomosis; current techniques requireinterrupting blood flow to suture, clip, or staple a bypass graft to thehost vessel wall.

[0016] One aspect of the invention provides fittings designed to exertradial force at the vessel attachment points to maintain bypass graftpatency. The fittings may be used to secure biological bypass graftsobtained by harvesting vessels from the patient or synthetic bypassgraft materials. When using harvested vessels, fitting embodimentspermit everting the harvested vessel to maintain intima to intimaapposition between the bypass graft and the host vessel. When usingsynthetic bypass graft materials, the fittings may be incorporated inthe bypass graft design to eliminate the step of attaching the bypassgraft to the fitting prior to deploying the bypass graft. The fittings,with bypass grafts attached, are advanced through the delivery systemand are secured to the host vessel wall at target locations.

[0017] The delivery systems enable inserting the fitting and bypassgraft into the host vessel without having to interrupt blood flowthrough the host vessel. One delivery system embodiment is a combinationof tear-away sheath, dilator, guidewire, and needle designed to beinserted into the host vessel at the desired anastomosis site. Afterattaching the bypass graft to the host vessel, the hub and valve of thetear-away sheath are configured to split so the entire sheath may beseparated and removed from around the bypass graft. This facilitatesattaching both ends of the bypass graft using the delivery system of theinvention and removing the tear-away sheath from around the intactbypass graft. A plunger is used to insert the bypass graft and fittingcombination through the sheath and into the host vessel. The plungeralso protects the bypass graft during insertion into the host vessel,especially when advancing past the hemostatic valve. As described inco-pending U.S. application Ser. No. 08/966,003 filed Nov. 7, 1997, thedilator and needle may incorporate advanced features, such as steering,sensing, and imaging, used to facilitate placing and locating the bypassgraft and fitting combination.

[0018] An alternative delivery system involves advancing a fittingembodiment through a puncture in the host vessel wall without the needto stop or re-route blood flow. The fitting may be partially insertedthrough an incision and rotated past the host vessel wall and into theinterior of the host vessel. Additionally, a guidewire may serve as apassage to rotate and advance the fitting into the interior of the hostvessel. Once inside the host vessel, the fitting may be secured therebysecuring the bypass graft to the host vessel.

[0019] In accordance with the invention, fitting embodiments produceanastomoses between harvested vessels and host vessels such that onlythe endothelial layer of the bypass graft is exposed to blood flow. Theinvention also describes fittings designed to permit retrograde flowpast the anastomosis site so as to maintain flow through the lesion andto branching vessels located proximal to the anastomosis site. A furtheraspect of the invention provides fittings having branches to accommodatemultiple bypass grafts using a single proximal anastomosis.

[0020] Further features and advantages of the inventions will beelaborated in the detailed description and accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

[0021]FIG. 1 shows a heart containing multiple bypass grafts positionedand secured to the host vessels;

[0022]FIG. 2 shows a bypass graft secured between a large vessel and asmall vessel;

[0023]FIG. 3 shows modular fittings secured to the host vessel wall andbranching into multiple passages and fittings that incorporate a supportstructure around the bypass graft;

[0024]FIGS. 4a and b are side-sectional views of a bypass graft supportstructure incorporating fittings;

[0025]FIG. 4c shows the support structure of FIG. 4a with a bypass graftattached to the fittings and secured to the host vessel at twolocations;

[0026]FIGS. 5a and b show a bypass graft attached to a fitting inaccordance with an embodiment of the invention;

[0027]FIGS. 6a to c show an embodiment in which suture is used to securethe bypass graft to the fitting;

[0028]FIGS. 7a to c show an alternative end-end fitting securing thebypass graft to the fitting and the fitting to the host vessel usingsutures;

[0029]FIGS. 8a to g show alternative end-end fittings;

[0030]FIGS. 9a to c show an everting tool;

[0031]FIGS. 10a to d show an alternative everting tool;

[0032]FIGS. 11a to i are end views of retaining rings used to bond thebypass graft to the fitting and/or the fitting to the vessel wall inaccordance with embodiments of the invention;

[0033]FIGS. 12a and b show a retaining ring in accordance with anembodiment of the invention;

[0034]FIGS. 13a and b show a retaining ring in accordance with anembodiment of the invention;

[0035]FIGS. 13c and d show an alternative expandable, collapsibleretaining ring used with bypass graft fittings;

[0036]FIGS. 14a to e show alternative retaining ring embodiments;

[0037]FIGS. 15a to d show alternative expandable, collapsible retainingring embodiments;

[0038]FIGS. 15e and f show an expandable, collapsible retaining ringincluding petals to make an end-end fitting able to produce an end-sideanastomosis;

[0039]FIG. 16 shows an expanding tool used to position retaining ringshaving eyelets;

[0040]FIGS. 17a to c show an expanding tool used to open the diameter ofand position the retaining ring shown in FIGS. 13c and d;

[0041]FIG. 18 shows a bypass graft attached to end-end fittings andsecured to the host vessel;

[0042]FIGS. 19a to d show a delivery system in accordance with anembodiment of the invention;

[0043]FIGS. 20a to c show an access device designed to puncture thevessel wall and insert a sheath into the vessel;

[0044]FIGS. 21a to c show an access device having a movable mechanism topuncture the vessel wall and insert a sheath into the vessel;

[0045]FIG. 22 shows an access device having dual movable mechanisms toindependently puncture the vessel wall and advance a sheath into thevessel;

[0046]FIGS. 23a and b show the access device of FIG. 21a incorporating astabilizing structure;

[0047]FIGS. 24a to i show the top views of alternative stabilizingstructures;

[0048]FIG. 25 shows a delivery system in accordance with an embodimentof the invention;

[0049]FIG. 26 shows a two-way plunger used to deliver the bypass graftand fitting combination through the sheath and into the host vessel;

[0050]FIGS. 27a to c show an alternative plunger embodiment;

[0051]FIG. 28 shows a bypass graft and fitting combination beinginserted through a sheath in accordance with a delivery systemembodiment of the invention;

[0052]FIGS. 29a to f show an introduction device used to deploy thebypass graft and fitting combination through an incision in the vesselwall;

[0053]FIG. 30 is a cross-sectional view of a bypass graft and fittingcombination attached to a vessel wall in accordance with an embodimentof the invention;

[0054]FIG. 31 shows a fitting embodiment using a latching mechanism tosecure a bypass graft to a vessel wall;

[0055]FIGS. 32a to c show a bypass graft secured to a host vessel usingend-side fittings in which a flange is used to reinforce the attachmentpoint;

[0056]FIGS. 33a and b show a retaining ring incorporating a supportmechanism that may be sutured to tissue away from the host vessel;

[0057]FIGS. 34a to d show a fitting incorporating flanges to secure abypass graft to a host vessel wall;

[0058]FIG. 35 is an end view of a clip used instead of sutures to attachthe flanges;

[0059]FIGS. 36a to e show an end-side fitting that may be delivered pasta vessel wall without the need for a sheath;

[0060]FIGS. 37a to e show alternative end-side fitting that may bedelivered past a vessel wall without the need for a sheath;

[0061]FIGS. 38a and b show an end-side fitting, incorporating aretaining ring with petals, designed to compress the host vessel wallbetween two fitting components;

[0062]FIGS. 39a to d show end-side fittings designed to compress thehost vessel wall between two fitting components;

[0063]FIGS. 40a to g show an end-side fitting specifically designed forhost vessels having small and medium diameters;

[0064]FIGS. 41a to h show radially expandable, collapsible end-sidefittings;

[0065]FIG. 42 shows a bypass graft and fitting combination attached to ahost vessel and designed to preserve flow proximal to the anastomosissite;

[0066]FIGS. 43a and b are close-up views of the bypass graft and fittingcombination shown in FIG. 42;

[0067]FIGS. 43c to g show alternative bypass graft and fittings designedto maintain retrograde blood flow;

[0068]FIG. 44 is an elevated view of a bypass graft and fittingcombination attached to a host vessel wall and incorporating a strainrelief around the fitting;

[0069]FIGS. 45a to c show “Y” fittings used to attach multiple bypassgrafts from a single vessel attachment point;

[0070]FIGS. 46a and b show tear-away sheath embodiments;

[0071]FIG. 47 shows a dilating sheath embodiment;

[0072]FIGS. 48a to d show an axial snap end-end fitting designed torapidly attach a bypass graft to the fitting;

[0073]FIGS. 49a to d show a radial snap end-end fitting designed torapidly attach a bypass graft to the fitting;

[0074]FIGS. 50a and b show a radial snap end-side fitting designed torapidly attach a bypass graft to the fitting;

[0075]FIGS. 51a to d show a compression tool designed to atraumaticallyadvance a compression ring over an end-side fitting;

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0076] The fittings and delivery systems of the invention are intendedto produce anastomoses between bypass grafts and host vessels to treatvascular abnormalities such as stenoses, thromboses, other occlusions,aneurysms, fistulas, or other indications requiring a bypass graft. Thesystems of the invention are useful in bypassing stented vessels thathave restenosed. Current approaches for treating stenosed stents havenot been successful at safely and reliably removing the lesion andopening the vessel lumen. Therefore the approach described by thisinvention, which produces a blood flow conduit around the stentedlesion, mitigates concerns associated with damaging the stent or formingemboli while removing deposits attached to the stent. The fittings arealso intended to secure and support the ends of transected vessels suchas those cut during organ transplantations. The embodiments of theinvention also provide mechanisms to secure branching vessels to areplacement graft during surgical procedures in which the branchingvessels would otherwise be occluded from blood flow (e.g. reattachingthe renal arteries, mesenteric artery, celiac artery, and intercostalarteries during treatment of abdominal aortic aneurysms that arepararenal, suprarenal, or thoracoabdominal in classification).

[0077] Referring more particularly to the drawings there is seen, inFIG. 1, bypass grafts secured to host vessels during coronary arterybypass grafting (CABG) procedures. Bypass graft 16 provides a blood flowpassage from the aorta to the right coronary artery. An end-side fitting18 is used to secure the proximal end of the bypass graft 16 to theaorta. A fitting 20 (end-side or end-end) is used to secure the distalend of the bypass graft to the right coronary artery. An in-line bypassgraft 22 provides a blood flow passage along a small or medium sizedvessel, such as a coronary artery, by securing the bypass graft to thehost vessel with end-end fittings 24 configured to shunt blood flowaround a diseased section of the host vessel. A bypass graft 26 issecured to the aorta with an end-side fitting and branches at 28, intoseveral distinct bypass grafts which are further secured to the leftanterior descending artery and circumflex artery using end-end orend-side fittings 20. The specific bypass grafts and fittings in theseexamples demonstrate representative applications for the fittings andshould not limit the scope of use for the embodiments of the invention.However, it should be noted that the combination of graft fittings(end-side and end-end) used to secure a bypass graft to a host vessel,along a host vessel, or between host vessels depends on the application.

[0078] Bypass Grafts

[0079] The bypass graft may be a synthetic graft material, harvestedvessel, or other tubular body structure, depending on the indication foruse. The harvested vessels may be an internal mammary artery, mesentericartery, radial artery, saphenous vein or other body tubing. Harvestedvessels may be dissected using newer minimally invasive, catheter-basedtechniques or standard surgical approaches. Fittings in accordance withthe invention are designed to attach bypass grafts to host vessels (orother tubular structures). The fittings used to position and attach suchbypass grafts are extensions of the collet and grommet embodimentsdescribed in U.S. application Ser. No. 08/966,003 filed Nov. 7, 1997 andincorporated herein by reference. The primary advantage of biologicalbypass grafts (e.g. harvested vessels) over currently availablesynthetic materials is the reduction in thrombosis especially when usingsmall diameter (e.g. (2 mm) bypass grafts. However, the fittings anddelivery systems of the invention are equally effective at positioningand securing all types of bypass grafts, biological and synthetic.

[0080] Synthetic bypass grafts may be manufactured by extruding,injection molding, weaving, braiding, or dipping polymers such as PTFE,expanded PTFE, urethane, polyamide, polyimide, nylon, silicone,polyethylene, collagen, polyester, composites of these representativematerials, or other suitable graft material. These materials may befabricated into a sheet or tubing using one or a combination of thestated manufacturing processes. The sides of sheet materials may bebonded using radiofrequency energy, laser welding, ultrasonic welding,thermal bonding, sewing, adhesives, or a combination of these processesto form tubing. The synthetic bypass graft may be coated, deposited, orimpregnated with materials, such as paralyne, heparin solutions,hydrophilic solutions, or other substances designed to reduce thrombosisor mitigate other risks that potentially decrease the patency ofsynthetic bypass grafts.

[0081] The primary advantage of synthetic bypass graft materials is theability to bond the bypass graft to the fittings prior to starting theprocedure or incorporate the fittings into the bypass graft by injectionmolding or other manufacturing process. Currently, synthetic bypassgrafts are indicated for blood vessels having medium and large diameters(e.g. >3 mm), such as peripheral vessels, tubular structures such as thefallopian tubes, or shunts for hemodialysis. However, medical devicemanufacturers such as Possis Medical, Inc. and Thoratec Laboratories,Inc. are evaluating synthetic bypass grafts for coronary indications. Inthis disclosure and the accompanying drawings, reference to bypass graftmay pertain to either biological bypass grafts such as harvested vesselsor synthetic bypass grafts, unless specifically stated.

[0082] As discussed in co-pending U.S. application Ser. No. 08/932,566filed Sep. 19, 1997 and co-pending U.S. application Ser. No. 09/966,003filed Nov. 7, 1997, support members may be incorporated into the graft.When using synthetic bypass grafts, the support members may be laminatedbetween layers of graft material. The synthetic bypass graftencompassing support members may be fabricated by extruding, spraying,injection molding, or dipping a primary layer of graft material over aremovable mandrel; positioning, winding or braiding the support memberson the primary layer; and extruding, spraying, injection molding, ordipping a secondary layer over the graft material/support membercombination. The support members may be fabricated from a metal, alloy(e.g. stainless steel), or polymer (e.g. nylon or polyester); however,the support members preferably have a shape memory. Support membersenhance the performance of the bypass graft by maintaining lumenalpatency, offering flexibility, and increasing the strength. Supportmembers fabricated from memory elastic alloys, such as nickel titanium,exhibiting stress-induced martensite characteristics further reinforcethe bypass graft and/or vessel wall and prevent permanent deforming uponexposure to external forces.

[0083] Alternatively, synthetic bypass grafts incorporating supportmembers may be fabricated using cellulosic materials such as regeneratedcellulose or cellulose acetate. Cellulosic materials may be extruded,wrapped, injection molded, or dipped to laminate the support membersbetween graft material layers. Cellulosics, and other such materialsthat have a high water adsorption rate, are relatively stiff whendehydrated and flexible when hydrated. This characteristic provides ameans to constrain a self-expanding material (i.e. the support members)in a reduced diameter since the cellulosic material in its dry, stiffstate counteracts the radial force of the self-expanding support membersthereby preventing the graft from expanding until it becomes hydrated,thus more flexible. Once the bypass graft is inserted through thedelivery system and into the vessel, the cellulosic material contactsfluid. As the graft material adsorbs fluid, it tends to become moreflexible, allowing the support members of the bypass graft to expandtowards its resting state urging the graft into intimate contact withthe vessel wall.

[0084]FIG. 2 shows a bypass graft 22 with one end attached to a largevessel 29 using an end-side fitting 30 and a second end secured to asmall or medium vessel 31 such as a coronary artery, using an end-sidefitting 32. Fittings 30 and 32 are oriented at an angle A between thebypass graft and the host vessel ranging between 30 and 90 degrees,selected to optimize the fluid flow from one end to the other. Rings 34secure portions 36 of the vessel walls 38 to the fittings.

[0085] Biological bypass grafts may be reinforced with supportstructures. This support structure may consist of a wire 40 wound into ahelix (FIG. 3) or braided into a mesh. Other reinforcing structures thatlimit expansion of bypass graft 22 may be used. The support structure isbonded to fittings at each end by spot welding, crimping, soldering,ultrasonic welding, thermal bonding, adhesively bonding, or otherbonding process, depending on the materials used. The support structuredefines a lumen into which the bypass graft is inserted. After advancingthe bypass graft through the support structure, the bypass graft issecured to the fittings at each end of the support structure. Thesupport structure reduces the potential for kinking the bypass graft,limits its radial expansion, prevents aneurysm formation, limitslongitudinal stretching, prevents excess twisting, and increases thegraft burst strength. By mitigating the failure mechanisms of biologicalbypass grafts such as the saphenous veins, such reinforcing structurescan improve the long-term durability and patency of biological bypassgrafts.

[0086] Fittings can branch into multiple passages to attach multiplebypass grafts from a single vessel attachment point. FIG. 1 shows abypass graft that is constructed with a bifurcation 28 and extends fromthe aorta to the left anterior descending and circumflex arteries. FIG.3 shows modular or branching fittings 42 that have threads 44 to secureother fittings 46 and bypass graft and fitting combinations. A fitting48 (also shown in FIG. 19d) is attached at a first host vessel location.Branching fitting 42 is threaded onto fitting 48 to produce a fluidtight seal. A bypass graft 22 and fitting 46 combination is threadedonto one extension of the branching fitting 42 producing a fluid tightseal. The opposite end of the bypass graft 22 is bonded to a secondvessel location. Additional bypass graft and fitting combinations may beattached to the branching fitting 42 to produce multiple passages from aprimary anastomosis. The fitting secured at the primary anastomosis mayhave a larger inner diameter than the branching bypass grafts to accountfor the increased cross-sectional area when considering multiple bypassgrafts and provide enough cardiac output for all branches. When branchesof the modular fitting 42 are not necessary, a cap 50 may be threadedonto the modular fitting 63 to close the desired branch and maintain afluid tight seal.

[0087] The support structure can be a synthetic graft formed into atube, with or without support members, as shown in FIGS. 4a to c. Asupport structure 52 can be fabricated from a polymer createdmacroporous to permit blood leaking through the bypass graft to flowoutside the support structure. To produce macroporous supportstructures, pores can be laser drilled through the support structurematerial. Alternative manufacturing processes-for creating pores may beused. Biological bypass grafts typically have branches that are suturedor stapled closed while harvesting the vessel and may leak for a periodof time immediately after implantation. Blood leaking through abiological bypass graft enclosed in a nonporous or microporous (e.g.pore size less than 8 microns) support structure may accumulate in thespace between the bypass graft and the support structure, possiblyconstricting or occluding the bypass graft. This depends on the pressuregradient from inside the biological bypass graft to the space betweenthe bypass graft and the support structure. For applications where thebiological bypass graft is completely impervious to leaking or theexternal surface of the biological bypass graft can be bonded to thesupport structure (e.g. using adhesives), nonporous or microporoussupport structures may be used.

[0088] Support structure 52 is preferably affixed to the fittings beforeattaching bypass graft 22 to the fittings. The support structurereinforces the entire length of the bypass graft. Using supportstructures that are not affixed to the fittings may cause kinking of thebypass graft between the anastomosis site and the end of the supportstructure. This defines a region where the bypass graft is notreinforced and a mismatch in compliance exists between a section ofbypass graft strengthened by the support structure and a section ofexposed bypass graft. Support structure 52 incorporates fittings at eachend to attach a harvested vessel 22 and secure the bypass graft to ahost vessel 29. A grasping tool 54, a suture with a noose or a wirehaving a distal gripping end such as forceps, is fed through the supportstructure to grab the end of the harvested vessel. As seen in FIG. 4b,the harvested vessel is pulled through support structure 52 such that alength of the harvested vessel extends beyond both ends of the supportstructure fittings. The ends of the harvested vessel are everted aroundthe support structure fittings (FIG. 4c) and secured at the notchedregions 56 of the fittings using retaining rings 34. Certain designs mayincorporate an electrode 58 along each fitting near the notched region.In this embodiment, blood flowing through the bypass graft 22 contactsthe endothelial layers of the harvested bypass graft and host vesselthereby minimizing the potential for thrombosis or biological reactionsto foreign materials. Other fitting configurations designed to produceend-end or end-side anastomoses, as discussed below, may be attached tothe support structure.

[0089] When microporous or nonporous support structures are used, thesupport structures serve dual purposes. They function as syntheticbypass grafts designed to produce end-end or end-side anastomoses atopposite ends of the bypass grafts. They also function as suturelessanastomosis devices to attach harvested vessels and reinforce thebiological bypass grafts. This minimizes the product portfolio requiredfor bypass grafting indications because a single device may reinforceand facilitate attaching harvested vessels between anastomosis sites andact as a synthetic bypass graft capable of producing suturelessanastomoses. In addition, these support structures enable usingharvested vessels in catheter-based applications where harvested vesselsdo not have enough inherent column strength to be atraumaticallyadvanced through a guiding catheter. The support structure protects theharvested vessel during deployment and reinforces the harvested vesselafter bypass graft attachment.

[0090] Fittings

[0091] Bypass graft fittings preferably are constructed from a metal(e.g. titanium), alloy (e.g. stainless steel or nickel titanium),thermoplastic, thermoset plastic, silicone or combination of theaforementioned materials into a composite structure. Other materials maybe used. The fittings can be coated with materials such as paralyne orother hydrophilic substrates that are biologically inert and reduce thesurface friction. Alternatively, the fittings can be coated with heparinor thrombolytic substances designed to prevent thrombosis around theattachment point between the bypass graft and the host vessel. Thefittings consist of one or more components designed to secure a bypassgraft to the fitting and secure the fitting to the vessel wall, toproduce a fluid tight bond between the bypass graft and the host vessel.The fittings may be used to produce end-end anastomoses for applicationswhere retrograde blood flow is not essential (e.g. total occlusions andin-line bypass grafting), end-side anastomoses for medium and smalldiameter vessels (e.g. peripheral vessels and coronary vessels) whereretrograde blood flow is essential, and end-side anastomoses for largediameter vessels (e.g. the aorta).

[0092] The fittings can include slots to maintain radial stiffness butincrease axial flexibility. The slots can extend radially around aportion of each fitting at specific intervals along the fitting. Theslots are formed by laser drilling, EDM, chemical etching or othersuitable processes. Alternatively, the slots can be fabricated duringinjection molding, scintering or other material forming processes,depending on the type of material. The fitting also can be formed from asheet of material laser drilled or chemically etched into a desiredpattern, and bonded at the sides into a tubular fitting containing theslots. The slots preferably are located on the proximal portion offitting to act as integrated strain relief to help prevent kinking ofthe attached bypass graft while permitting slight motion at theanastomosis site. The slots may also extend throughout the length of thefitting since the radial stiffness is sufficient to keep the vessel wallopen at the insertion site into the host vessel. As described later, theslots also may be configured to facilitate compressing the fitting intoa reduced diameter for insertion through a sheath having a smallerdiameter than the expanded diameter of the fitting.

[0093] Fittings and fitting components can be made from biodegradable orbioabsorbable materials. Such fittings can be configured to break downafter a set time period, e.g. three weeks, during which time theanastomosis site is reinforced with tissue in-growth producing asufficiently strong bond between the bypass graft and the host vessel.This approach is useful when bonding biological bypass grafts to hostvessels or reattaching to host vessel ends. Suitable bioabsorbablepolymers include poly (L-lactic acid), polycaprolactone, poly(lactide-co-glycolide), poly (hydroxybutyrate), poly(hydroxybutyrate-co-valerate), polydioxanone, polyorthoester,polyanhydride, poly (glycololic acid), poly (D, L-lactic acid), poly(glycololic acid-co-trimethylene carbonate), polyphosphoester,polyphosphoester urethane, poly (amino acids), cyanoacrylates, poly(trimethylene carbonate), poly (iminocarbonate), copoly (ether esthers)(e.g., PEO/PLA), polyalkylene oxalates, polyphosphazenes, as well asbiomolecules such as fibrin, fribrinogen, cellulose, starch, collagenand hyaluronic acid.

[0094] The bioabsorbable or biodegradable fittings may also incorporatethe ability to diffuse drugs at a controllable rate at the anastomosissite. Manufacturing methods to provide this feature in fittings includeadding a therapeutic agent to the base material during fabrication ofthe fitting components, and applying a coating containing a therapeuticagent after the fitting is fabricated. The approach can combine thesemethods. Suitable therapeutic coatings include dexamethasone,tocopherol, dexamethasone phosphate, aspirin, heparin, coumadin,urokinase, streptokinase, and TPA, applied by spraying, dipping or othermeans. The fittings also can be seeded with endothelial cells.

[0095]FIGS. 5a and b show an end-end fitting 60 designed to securebypass grafts constructed from an internal mammary artery, radialartery, saphenous vein, or other harvested vessel such that only theendothelial layer 62 of the bypass graft is exposed to blood flow.Bypass graft 22 is fed through the interior of the fitting, everted andwrapped around the distal end. A grasping tool 54 (FIG. 4) is used topull the bypass graft through the fitting, especially when using longfittings. A groove 56 is fabricated near the distal end of fitting 60 toprevent axial movement of retaining ring 34, thus retaining the bypassgraft after positioning the retaining ring over the bypass graft andfitting combination. The retaining rings are designed to produce aninterference fit between the bypass graft and fitting to hold the bypassgraft in place and prevent leaking at the attachment point. Multipleretaining rings may be used to secure a bypass graft to a fitting.

[0096] An everting tool preferably is used to wrap the bypass graftaround the fitting prior to securing the bypass graft to the fitting. Aneverting tool 64 shown in FIGS. 9a to c is inserted into the distal endof the bypass graft 22 to be everted around fitting 60. The distal end66 of the everting tool is designed to fit through the lumen of thebypass graft and the inner diameter of the fitting 60. Proximal to theeverting tool distal end is a tapered or curved region 68 which causesthe bypass graft 22 to wrap around the distal end of the fitting 60 asthe bypass graft and fitting are advanced over the everting tool 64. Aretaining ring 34 is housed around the everting tool 64 and is advancedover the bypass graft and fitting to secure the bypass graft 22 to thefitting 16.

[0097] This eversion process can be performed with the end of the bypassgraft intact. Alternatively, one or more short, longitudinal incisionsmay be created at the end of the bypass graft. The sides of the cutbypass graft are pulled over the distal end of the fitting causing thebypass graft to wrap around the fitting. This method is particularlyuseful when using harvested vessels from patients that are partiallydiseased reducing the elasticity of the vessel and inhibiting theability to evert the intact vessel over the fitting.

[0098] Another everting tool 70 (FIGS. 10a to d) uses an expansionmechanism to mechanically wrap the bypass graft around the distal end ofthe fitting. Strands 72 are attached together and to a stylet 74 with adistal cap 76 by spot welding or soldering the distal ends of thestrands and distal end of the stylet together and covering this jointwith a shrink tubing or adhesive. The proximal ends of the strands 72are attached to everting tool 70. Stylet 74 is attached to a movablecontrol knob 75 for moving the stylet relative to the rest of evertingtool 70. As the knob is pulled, the strands bow radially outward causingthe distal end of the bypass graft to expand. The bypass graft is thenwrapped around the fitting 60 by advancing the expanded end of thebypass graft over the fitting.

[0099] As shown in FIGS. 6a to c, the bypass graft 22 may be sutured orclipped to the fitting. Fitting 60, shown in FIG. 6a, incorporates holes78 at spaced intervals around its circumference. The bypass graft is fedthrough and wrapped around the fitting as described above. The bypassgraft is then secured by feeding sutures 80 through the holes 78 andtying the bypass graft to the fitting 60. Conventional suturingtechniques may be used to secure the bypass graft to the fitting.Alternatively clips or staples may be used to secure the bypass graft tothe fitting.

[0100]FIGS. 7a to c show another method of suturing a bypass graft to afitting. The fitting 60 has notches 56 designed to provide anindentation to secure a bypass graft using the retaining ring or suture.Once the bypass graft 22 is advanced through the fitting and evertedaround the distal end, one or more strands of suture 80 are tied aroundthe everted bypass graft and located in the notches 56 thereby producinga fluid tight seal. Sutures may also be used to attach bypass grafts tothe outside of a fitting without everting the bypass graft. In addition,as shown in FIG. 7c, an end-end anastomosis may be produced between abypass graft and fitting combination, such as that shown in FIGS. 7a andb, and a host vessel 29. The host vessel 29 is advanced over the bypassgraft and fitting combination or the bypass graft and fitting areinserted into the host vessel 29 and suture 80 is tied around the hostvessel, positioned in the notches of the fitting. This not only securesthe host vessel to the bypass graft and fitting combination, but itproduces a fluid tight seal.

[0101] An alternative mechanism to produce end-end anastomoses betweengrafts and host vessels is to insert the graft incorporating end-endfittings through the delivery system of the invention (described below)into the host vessel. Fittings similar to the compressible retainingrings shown in FIGS. 15a to d and having a compressible or deformablecharacteristic but incorporating a shape memory, are either laminated(synthetic grafts) or wrapped (synthetic or biological grafts) betweenlayers of the graft material. When wrapping the end-end fitting betweenlayers of graft material, the graft is inserted through the innersurface of the fitting and is wrapped at least once around the outersurface of the fitting. The graft material may be rolled around theend-end fitting to wrap the material more than once around the fitting.Then, adjacent layers of graft material are sutured, ultrasonicallywelded, thermally bonded or adhesively attached to incapsulates thefitting between the layers.

[0102] Once the ends of the graft are positioned at the correctanastomosis sites, the end-end fittings are sutured to the host vesselby inserting sutures around or through the end-end fitting from theexterior surface to the host vessel. The fittings are constructed from amemory elastic alloy, silicone, or polymer having a stiffness andelasticity selected to impose a shape memory to the resting geometry.Once the end-end fittings are positioned within the host vessel, theyreturn towards their pre-shaped geometry causing them to contact theinterior surface of the host vessel wall. The operator can determine theposition of the end-end fittings within the host vessel by feeling for achange in compliance along the vessel. After locating the fittings, theoperator uses attached needles to insert sutures through the vesselwall. The needles then are used to pass sutures either around or throughthe fittings. When memory elastic alloys are used for the fittings, thesutures must pass around the fittings, but may pass through the graftmaterial. When silicone or polymers such as urethane having a relativelylarge percent elongation characteristic are used for the fittings, thesutures may pass through the fittings. Then the needles are used to passthe sutures back through the vessel wall on the opposite end of theend-end fitting. Alternatively, as shown in FIGS. 6a to c and describedabove, the end-end fitting may incorporate holes that accept sutures forsecuring the fitting to the host vessel. In this case, a needle is usedto puncture the vessel wall and insert the attached suture through onehole in the fitting and pass back through the vessel wall. After thesutures are placed, they are knotted to secure the fittings to thevessel wall. This method is used to secure bypass grafts with end-endfittings placed inside the host vessel. This method also may be used tosecure reinforcing grafts with end-end fittings that are placedcompletely within the host vessel through a delivery system embodimentof the invention.

[0103]FIGS. 8a to d show various fitting embodiments that enableattaching bypass grafts using retaining rings. FIG. 8a shows a fittingembodiment that has steps 82 to accommodate varying diameter vesselswith a single fitting. Fitting 83 (FIG. 8b) incorporates a notchedmiddle region 84 to accept one or more retaining rings for securing thebypass graft to the fitting and/or the fitting to the host vessel. Thefitting can have a slotted middle region to enable suturing or clippingthe bypass graft to the fitting and/or the fitting to the host vessel. Afitting 86 (FIG. 8c) incorporates a notched distal region 88 to acceptthe bypass graft and retaining ring and create a smooth transition fromthe external surface of the fitting to the external surface of theretaining ring and bypass graft. This prevents excess material thatcould hinder insertion of the bypass graft and fitting combinationthrough the delivery system. The devices shown in FIG. 8 may function asretaining rings to compress the bypass graft against a fitting as theretaining ring is advanced over the bypass graft toward a fittinginterface.

[0104]FIG. 8d shows a snap fitting 90 designed to facilitate bonding thebypass graft. A distal piece 92 of the snap fitting incorporatesextensions 94 to lock distal piece 92 to mating teeth 96 of a proximalsnap fitting piece 98. The proximal piece is tapered to accommodate arange of bypass graft diameters. The bypass graft is inserted throughproximal piece 98 and everted over the external surface of the proximalpiece. Alternatively, the bypass graft is positioned over the exteriorsurface of proximal piece 98. Then, distal piece 92 is advanced over thebypass graft and proximal piece interface, and is locked to the teeththereby securing the bypass graft to the proximal piece. The distalpiece is configured for end-end anastomoses. It can be modified toaccommodate end-side anastomoses. The bypass graft and snap fittingcombination can be secured to a host vessel using retaining rings (forend-end anastomoses) or compression rings (for end-side anastomoses), aswill be described below. Alternatively, a second distal snap fittingpiece like 92 designed to fit over distal piece 92 may be used to securethe host vessel to the bypass graft and snap fitting combination.This-is especially useful when reattaching severed vessel ends.

[0105]FIGS. 11a to f show retaining rings used to secure the bypassgraft 22 to the fitting. In FIGS. 11a to d, the retaining rings arepre-shaped and have rectangular, circular, or elliptical cross-sectionswith eyelets 100 that facilitate positioning the retaining ring over thefitting and may be used to suture the retaining rings closed foradditional support.

[0106] A retaining ring 102 in FIGS. 11a and b is preshaped to be woundbeyond a single turn. When eyelets 100 are squeezed together, thediameter of the retaining ring enlarges making it easier to positionover the bypass graft and fitting combination. Rings 104 and 106 inFIGS. 11c and d have the coiled wire extending short of a single turn.When eyelets 100 are spread apart, the diameter of the retaining ringenlarges. An expanding tool 108 shown in FIG. 16 has two extensions 110insertable through the eyelets of the retaining ring. The expanding toolis used to expand the retaining rings above by squeezing the eyeletstogether for retaining ring 102 or spreading the eyelets apart for theretaining rings 104 and 106.

[0107]FIG. 11e shows a retaining ring 112 that incorporates a ratchetmechanism 114. As the distal end 116 of the retaining ring is advancedthrough the ratchet mechanism, a latch 118 prevents the retaining ringfrom opening by grasping the teeth of the retaining ring. This locks theretaining ring around the bypass graft and fitting interface producing afluid tight fit. This retaining ring may also be used to secure the hostvessel to the graft fitting, as in FIGS. 43a and b.

[0108] A retaining ring 120 shown in FIG. 11f is similar to ring 104 butincorporates looped regions 122. This retaining ring atraumaticallyslides over the bypass graft and fitting combination without the need topull the ends of the retaining ring apart. The distal region of theretaining ring spreads open while advancing over the bypass graft andfitting combination and springs closed after extending past the maximumdiameter of the bypass graft and fitting combination. Alternatively, theretaining ring can be an enclosed circle and exhibit an elasticcharacteristic to permit stretching into an enlarged diameter andcompress around the bypass graft to fitting interface when released.

[0109] A retaining ring 124 shown in FIG. 11g is a preshaped memberwound beyond a single turn and having radiused edges and ends. Onerepresentative fabrication process for the preshaped retaining ringinvolves forming the raw material into a desired geometry and exposingthe material to sufficient heat to anneal the material into thispredetermined shape. This process applies to metals, alloys (e.g. nickeltitanium) and polymers. The preshaped retaining ring configuration isexpanded by inserting the expansion tool into the middle of theretaining ring and opening the expansion tool thereby enlarging thediameter of the retaining ring. Once the retaining ring is positioned,the force causing the retaining ring to enlarge is removed causing theretaining ring to return towards its preformed shape thereby compressingthe bypass graft against the fitting. This retaining ring may also beused to secure a fitting to a host vessel since this retaining ring maybe expanded to expose an opening between opposite ends adapted forplacement over the host vessel. Once positioned over the host vessel tofitting interface, the retaining ring is allowed to return towards itspreformed shape thereby compressing the host vessel against the fitting.Retaining ring 124 can be manufactured from a deformable material andcrimped over the bypass graft to fitting interface or host vessel wallto fitting interface for securing purposes.

[0110]FIG. 11h shows another retaining ring 126 that does notincorporate elastic memory characteristics. This retaining ring isopened for positioning around the bypass graft to fitting interface orthe host vessel to fitting interface and is closed, causing teeth 128 toengage and lock the retaining ring in the closed position. Furtherclosing the retaining ring causes the diameter to decrease and exertadditional compression force. FIG. 11i shows another retaining ring 130having preshaped members 132 wound beyond a single turn. This embodimentalso permits expansion of the retaining ring to facilitate positioning,but is configured to form a complete ring in its resting shape.

[0111]FIGS. 12a and 12 b show a retaining ring 136 with an end extension138 that fits through a slot. FIGS. 13a and b show a retaining ring 140with eyelets 100 and a pivot point 142.

[0112] The retaining ring shown in FIGS. 13c and d has semicircularsections 144 for increased stiffness. The retaining ring may befabricated from a metal, alloy, thermoplastic material, thermoset, orcomposite. However, the retaining ring must permit approximately 30%enlargement in diameter without becoming permanently deformed. Thus,after placement, the retaining ring will collapse around the bypassgraft and fitting interface to form a secure seal.

[0113] Other retaining ring embodiments, shown in FIGS. 14a to e andFIGS. 15a to d, are fabricated as enclosed rings but enable expansion toposition around the bypass graft to fitting interface. The retainingrings 146-154 shown in FIGS. 14a to e and FIGS. 15a to d are enlarged todeploy around the bypass graft and fitting combination and are allowedto return towards their preformed shape, once positioned, therebysecuring the bypass graft to the fitting and providing a fluid tightseal. Another expandable retaining ring 156, shown in FIGS. 15e and f,incorporates petals 158 so an end-end fitting may be used to produce anend-side anastomosis.

[0114] An alternative expansion tool 160 is shown in FIGS. 17a to c.This expansion tool is designed to expand the retaining ring by pullingthe ends of the retaining ring relative to an anchor point. A stylet 162holds a retaining ring 164 in place and produces the anchor point. Legs166 of the expansion tool have notches 168 positioned at the edges ofthe retaining ring. The legs rotate about a pivot pin 170 fixed to thehandle. When a knob 172 is advanced relative to the handle, the legsmove radially outward thereby opening the diameter of the retainingring. Once positioned around the bypass graft and fitting interface,tension on the knob is released allowing the retaining ring to compressthe bypass graft against the fitting. The expansion tools describedabove may also be used to position retaining rings around a host vesselto fitting interface producing a fluid tight bond between the bypassgraft and the host vessel.

[0115] Alternative embodiments of the invention involve attaching thebypass graft around the exterior of the fitting as opposed to feedingthe bypass graft through the interior and wrapping it around the end ofthe fitting as discussed above. For example, FIG. 18 shows a bypassgraft 22 secured around the exterior of fittings 170 using retainingrings 34. The bypass graft 22 is advanced over the exterior of fitting170 and is secured with a retaining ring 34, suture 80, or staples (notshown).

[0116] Delivery Systems

[0117] Conventional anastomosis techniques require a relatively largeincision through the vessel wall and use sutures, commercially availableclips, or stapling devices to bond the end of the bypass graft to theexposed edges of the vessel wall. In certain cases, the structuralintegrity of the vessel wall may be weakened causing the vessel tocollapse at the anastomosis site, especially when the bypass graft isnot appropriately aligned to the host vessel incision. Therefore, thedelivery system embodiments of the invention are designed to quicklyaccess the host vessel through a small puncture in the vessel wall. Assuch, the delivery systems are designed to prevent excess blood losswhen accessing the host vessel and deploying the bypass graft andfitting combination, thereby eliminating the need to stop or re-routeblood flowing through the host vessel. This approach also improves theleak resistance around the fitting due to elastic compression of thevessel wall around the fitting and automatically aligns the bypass graftto the host vessel wall at the anastomosis site.

[0118] The delivery system embodiment depends on the application. Forcatheter-based bypass grafting applications, as discussed in U.S.application Ser. No. 08/966,003 filed Nov. 7, 1997, a catheter (e.g.guiding member) is intralumenally advanced to the proximal anastomosissite. A puncture device (e.g. needle) is used to perforate the vesselwall and enable advancing a guiding member exterior to the vessel. Adilating member expands the opening to atraumatically advance theguiding member through the vessel wall. A balloon may be attached to theguiding member and inflated to restrain the guiding member outside thehost vessel and prevent leaking at the puncture site; the balloon wouldbe deflated while the guiding member is advanced through the vesselwall. The catheter is then manipulated (e.g. steered, advanced,retracted, and/or rotated) to the distal anastomosis site. The puncturedevice is used to perforate the vessel wall and access the interior ofthe vessel at the distal anastomosis site. A guidewire may be advancedthrough the puncture device or the puncture device may function as aguidewire to provide a passage to advance the guiding member into theinterior of the host vessel at the distal anastomosis site. Once theguiding member is advanced through the puncture and into the interior ofthe host vessel, the bypass graft is advanced inside or outside theguiding member to the distal anastomosis site. A stylet may be used toadvance the bypass graft along the guiding member or maintain theposition of the bypass graft as the guiding member is retracted. Theballoon attached to the guiding member may again be inflated to keep theguiding catheter within the vessel at the distal anastomosis site andprevent leaking. The bypass graft is secured to the host vessel at thedistal anastomosis site. Then, the guiding member is retracted so thebypass graft is able to contact the host vessel wall at the proximalanastomosis site. If a balloon was inflated to maintain the position ofthe guiding member within the vessel, it must be deflated prior toretracting the guiding member through the vessel wall. The bypass graftis then secured to the host vessel wall at the proximal anastomosis siteand the guiding member is removed leaving the bypass graft as a conduitfor blood to flow from the proximal anastomosis to the distalanastomosis. As previously stated, the fittings used to secure thebypass graft to the host vessel wall at the proximal and distalanastomosis sites depends on the application and whether retrogradeblood flow through the anastomosis site is desired.

[0119] For surgical applications, physicians are able to access theanastomosis sites from the exterior surface of the host vessel(s).Unlike the catheter-based approach where the bypass graft is advancedpast the distal end of the delivery catheter during deployment, thedelivery system of the surgical approach must permit removal after bothends of the bypass graft are secured and the delivery system residesaround the attached bypass graft. FIGS. 19a to c show representativesteps to position a bypass graft and fitting combination through avessel wall. A needle 172 is inserted through a dilator 174 that hasbeen inserted through a sheath 176. The needle, dilator, and sheathcombination is positioned at the target vessel location. Especially forminimal access procedures involving endoscopic visualization andmanipulation through small incisions, sensors may be incorporated in theneedle, dilator, and/or sheath to position the delivery system at thetarget location. As described in U.S. application Ser. No. 08/966,003filed Nov. 7, 1997, the sensors can include ultrasonic transducers, suchas those fabricated from piezoelectric material, doppler crystals,infrared transducers, or fiberoptics. Alternatively a lumen may permitthe injection of radiopaque contrast material within the vessel toverify the position using fluoroscopy.

[0120] Needle 172 is used to puncture the vessel wall 38 and is advancedinto the interior of the host vessel 29. The needle may be designed witha tapered or stepped distal end to restrict movement of the needlebeyond the end of the dilator and prevent perforating the opposite sideof the vessel or unwanted anatomy. A guidewire (not shown) may beadvanced through the needle to provide a path over which the dilator andsheath may be advanced. When using a guidewire, the needle may beretracted to prevent unwanted perforations or abrasions to the hostvessel or adjacent anatomy. Dilator 174 is then advanced over the needleor guidewire and into the host vessel. Subsequently, the needle (if notalready retracted to insert the guidewire) may be removed from thevessel or retracted inside the dilator. The dilator is tapered toprovide a smooth transition when advancing the dilator through thevessel wall. The vessel wall inherently forms a seal around the dilatorpreventing excess blood leakage from the vessel.

[0121] Sheath 176 has a radius or tapered distal end 178 and forming asmooth transition from the dilator to the body of the sheath iscontained around the dilator. Once the dilator is positioned within thevessel, the sheath may be advanced over the dilator and into the vesselas shown in FIG. 19b. At this point, the dilator may be removed. Thistechnique of inserting a sheath into a vessel over a dilator and needleis commonly used by physicians when performing the Seldinger techniqueduring catheterization procedures or inserting I.V. catheters into veinsfor withdrawal of blood or introduction of medicines. The sheath anddilator may be constructed from polyethylene, or other polymer that maybe extruded or molded into a tube. The sheath and dilator mayincorporate a braided layer laminated between two polymer layers toresist kinking and improve the column strength and torque response. Ataper and radius may be formed in the distal end of the dilator andsheath by thermally forming the raw tubing into the desired shape. Inaddition, the sheath may incorporate a softer distal tip fabricated bythermally bonding a short section of lower durometer tubing to thesheath or tapering the thickness of the sheath tubing.

[0122] Hubs 180 and 182 on the sheath and dilator respectively may befabricated from polycarbonate, polyethylene, PEEK, urethane or othermaterial, which may be injection molded, adhesively bonded,ultrasonically welded, or thermally bonded to the tube. Hub 180 containsat least one and preferably two grooves, slits, or series ofperforations along the hub to enable the operator to split the hub whenremoving the sheath from around the bypass graft. Hub 180 houses ahemostatic valve 184 constructed of silicone, urethane, or othermaterial having a low durometer and a large percent elongationcharacteristic. The hemostatic valve prevents excess blood loss throughthe sheath when positioned inside the vessel. The valve alsoincorporates at least one groove, slit, or series of perforations topermit separation when tearing the sheath from around the bypass graft.A side port may be included to aspirate and flush the sheath. The hubmay alternatively be a separate piece from the tear-away sheath suchthat it may be independently removed from around the bypass graft. Thishub would include a luer fitting to enable securing onto a mating pieceof-the tear-away sheath, or other mechanism to permit removablyattaching the hub to the tear-away sheath. This hub may incorporate atleast one groove, slit, or series of perforations to enable splittingthe hub to form an opening to remove the hub from around the bypassgraft. Alternatively, the hub may include a slot, which during use isclosed to prevent fluid from leaking, but can be aligned to form anopening for removal from around the bypass graft.

[0123] As shown in FIGS. 19c and d, the sheath provides a mechanism toinsert a fitting. In FIG. 19d, the bypass graft is not attached to thefitting 48 prior to insertion into the vessel 29. However, the bypassgraft may be attached to the fitting prior to inserting the fitting intothe vessel. A plunger 186 will vary depending on whether the bypassgraft 22 is attached to the fitting before or after inserting thefitting into the host vessel.

[0124] After securing the bypass graft to the fitting and advancing thefitting into the host vessel, as previously described, the bypass graftand fitting combination must be attached to the vessel wall. For someapplications, the fitting may be attached to the host vessel prior tosecuring the bypass graft to the fitting, as seen in FIG. 19d.

[0125] The delivery system used to access the vessel and position asheath through the vessel wall may be consolidated into a singlepuncture device. The puncture device 190 shown in FIGS. 20a to cincludes a handle 192 designed to push a perforating member 194 anddilating member 196 through the vessel wall and into the vesselinterior. A sheath 198 is positioned around the dilating member fordeployment through the vessel wall. A guidewire may also be advancedthrough the perforating member once positioned inside the vessel toprovide a line to advance the dilating member and sheath withoutperforating the opposite end of the vessel wall or adjacent anatomy.This puncture device also facilitates incorporating advanced features,such as forward looking imaging and steering, since the handle providesa structure to connect transducer leads and acts as an anchor from whichto retract pull-wires and deflect the distal end of the puncture device.

[0126] The puncture device 200 shown in FIGS. 21a to c further includesan actuator 202 to advance a perforating member 204 and dilating member206 relative to a handle 208. This mechanism provides more controllablemovement of the perforating member and dilating member. An adaptation ofthe puncture device is shown in FIG. 22. This puncture device 210includes dual actuators used to more precisely puncture the vessel walland advance the dilating member and sheath. When advancing the proximalactuator 212 forward, a perforating member 204, dilating member 206, andthe sheath 198 are advanced. However, retracting the proximal actuator212 pulls only the perforating member. This permits covering the tip ofthe perforating member within the dilating member after obtaining accessthrough the vessel wall. Since the perforating member is movablerelative to the dilating member, a hemostatic valve is formed betweenthe perforating member and dilating member to prevent blood from flowingback through the gap between the perforating member and dilating member.Pushing the distal actuator 218 advances the dilating member and sheath.This permits advancing the dilating member and sheath into the vesselwithout the risk of puncturing the opposite side of the vessel ordamaging adjacent anatomy with the perforating member.

[0127] More actuators may be added to the puncture device or theoperation of the illustrated actuators may be modified. For example, oneactuator may be used to facilitate advancing a guidewire through theperforating member and dilating member once access into the vessel hasbeen obtained. A single actuator may be used to advance the perforatingmember beyond the dilating member when advanced; this actuator wouldalso be spring-loaded so the resting position of the perforating memberis such that the tip is covered inside the dilating member.

[0128] Another feature that may improve the performance of the puncturedevice is a stabilizing extension. The stabilizing extension 220 shownin FIGS. 23a and b is formed from two legs shaped into a “V”. The legsmay be fabricated from a metal or polymer and have a circular,elliptical, or rectangular cross-section. The stabilizing extension 220is designed to decrease the movement of the vessel relative to thepuncture device. This is especially important when accessing thecoronary vessels. Several alternative configurations for the stabilizingextension are shown in FIGS. 24a to i. Alternative stabilizingextensions, as shown in FIGS. 24h and i, may be configured to fit aroundthe vessel to better stabilize the puncture device relative to the hostvessel.

[0129] As shown in FIG. 25, a sheath 222 may be fabricated with at leastone groove 224 (or a slit or series of perforations) formed along thetube and hub 226 to provide a guide to tear-away the sheath along atleast one side, after securing the bypass graft to the vessel wall.Alternatively, the sheath may include a section of tubing materialalready split into at least two sections such that the sheath tubingtends to continue to split into two pieces as the two sections arepulled apart. The ability to split is essential to removing the sheathfrom around a bypass graft 22 when the sheath is unable to slide pastthe opposite end of the bypass graft. When incorporating supportingmaterial into a tear-away sheath to improve column strength, thismaterial should ensure the sheath may be split along the grooves, slits,or perforations formed in the sheath. This supporting material may befabricated into two braided sections, or other support member sectionsoriented on opposite sides of the sheath such that the grooves residealong the spaces between the braided sections. Alternatively, thesupporting material may be strands of wire (stainless steel, nylon,etc.) laminated between layers of sheath material and oriented axiallyalong the longitudinal axis of the sheath.

[0130] A plunger 228 is designed to insert bypass graft 22 and a fitting230 as an attached unit, therefore it includes a lumen to pass bypassgraft 22 while inserting the fitting into the host vessel. A plunger isessential when inserting biological bypass grafts or synthetic bypassgrafts that do not have adequate column strength to be pushed throughthe hemostatic valve of the sheath. In addition, the plunger protectsthe bypass graft while inserting the bypass graft through the tubing andhemostatic valve of the tear-away sheath. After use of the plunger toadvance one side of the bypass graft at a first vessel location, it mustbe removed. The plunger may be retracted beyond the opposite end of thebypass graft, or the plunger is split along at least one groove 232,slits, or perforations incorporated along the side(s) of the plunger.Then a plunger similar to plunger 228 is used to insert the opposite endof the bypass graft, attached to a fitting, through a second sheathinserted at a second vessel location. After attaching the second end ofthe bypass graft to the host vessel, the plunger is contained betweenthe ends of the attached bypass graft and must be removed by tearing theplunger along the groove, slit, or series of perforations. The tear-awaygroove must permit splitting the plunger wall and a hub 234 along atleast one side to remove the plunger from around the bypass graft. Tofacilitate removal from around the bypass graft, the plunger (andtear-away sheath above) preferably incorporates grooves, slits, orperforations on two sides of the plunger to enable separating the tubeand hub.

[0131] As shown in FIG. 25, a retaining ring 236 may also be used tobond a bypass graft to the fitting from the interior of the fitting 230.In this embodiment, the fitting has an internal groove 224 to acceptretaining ring 236 which is wound into a smaller diameter and insertedinside the bypass graft and fitting combination. When the constrainedretaining ring is released, it expands to compress the bypass graft 22between the retaining ring and fitting.

[0132]FIG. 26 shows a bypass graft assembly containing fittings 60already attached at bypass graft 22 ends and an alternative plunger 238preloaded onto the bypass graft. This plunger is designed with the hub240 located at the middle of the plunger to facilitate inserting bothends of the bypass graft and attached fittings without having to removeand reposition the plunger before inserting the second end of the bypassgraft. The plunger has grooves, slits, or perforations 242 along atleast one side of a plunger tube 244 and hub 240 to permit removal ofthe plunger after positioning and attaching the bypass graft at bothends.

[0133] Another plunger embodiment is shown in FIGS. 27a to c. Thisplunger 246 includes an axial slot through the entire length of theplunger. The slot enables pulling the plunger from the side of thebypass graft when removing the plunger and permits pressing the plungerover the side of the bypass graft when placing the plunger over thebypass graft. One end 248 of the plunger has a short length stepped downto form a smaller outer diameter that fits inside the inner diameter ofthe fitting and provides a stable anchor to insert and manipulate thefitting during delivery of the bypass graft and fitting combination intothe vessel. The other end 250 of the illustrated plunger has the innerdiameter reamed out and notched for a short length to fit over the outerdiameter of the bypass graft and fitting combination duringmanipulations. The notched region can alternatively be configured toextend a sufficient length such that the plunger covers the fittingexterior, to protect the fitting during insertion through the sheath.This especially important when inserted end-side fittings that requireconstraining the petals in a reduced diameter profile for advancing thefitting and bypass graft combination through the sheath. This also helpsconstrain foldable or compressible fittings in their reduced diametersfor insertion through a sheath having a smaller diameter than theexpanded diameters of the fittings. Since this plunger maintains itsintegrity upon removal from the bypass graft, it may be used to deploymultiple bypass graft and fitting combinations.

[0134]FIG. 28 is an enlarged view of sheath 176 inserted into hostvessel 29 with dilator 174 removed, and with bypass graft 22 evertedabout fitting 48 and retained by ring 34.

[0135] For situations where blood flow is occluded and an incision hasbeen made through the vessel wall, a modified hockey stick introducermay be used to insert the bypass graft and fitting combination into thehost vessel. FIGS. 29a to f show a “hockey stick” introducer 252 havinga tapered distal end and a partially enclosed body. This hockey stickintroducer is advanced through the incision and expands the vessel wallso the bypass graft and fitting combination may be advanced through thehockey stick introducer lumen and into the host vessel without catchingthe top part of the fitting on the vessel wall. This is especiallyimportant when the bypass graft and fitting combination has an outerdiameter larger than the inner diameter of the vessel where the hostvessel must be expanded to insert the bypass graft and fittingcombination. The hockey stick introducer may incorporate an extensionperpendicular to the longitudinal axis that provides a handle tomanipulate the hockey stick introducer. In addition, the hockey stickintroducer may incorporate at least one spring-loaded jaw to grab thehost vessel wall after access has been obtained and permit manipulatingthe expanded host vessel by using the hockey stick introducer. This isespecially useful when reattaching severed vessels, which requiressignificant manipulations while repositioning the host vessel ends forbonding.

[0136] Additional Delivery System Features

[0137] As previously described in U.S. application Ser. No. 08/966,003filed Nov. 7, 1997, the needle and dilator may incorporate a number ofadditional features to facilitate positioning at the host vessel. Anumber of sensors may be placed within the tapered region of the dilatorsuch that they face axially or laterally with respect to the axis of thedilator lumen. As a result, imaging modalities may be directed forwardor around the periphery of the dilator. For both configurations, thesensors may be oriented around the dilator at known angular increments.Sensors used to position the delivery system include-ultrasonictransducers, such as those fabricated from piezoelectric material,infrared transducers, or fiberoptics. Four ultrasonic transducers may beplaced around the dilator separated by 90 degrees to provide a3-dimensional interpretation of anatomic structures in front of thedilator to better detect the host vessel. Conventional phased arrayimaging modalities may be used to derive images extending distal to thedilator or around the dilator circumference. Sensors may be placed atthe distal end of the needle to facilitate positioning the needle at thetarget vessel location. These sensors may be used in concert with thedilator sensors to provide better imaging resolution and determine thelocation of the needle tip relative to the end of the dilator.

[0138] Another feature which may be used in the dilator and needle isthe inclusion of steering, unidirectional or bidirectional. A steeringmechanism may be positioned within the sheath, dilator, and/or needle.Typically, the steering mechanism consists of a pull-wire terminating toa flat spring (constrained with a thin walled tubing such as PET orPTFE) or collar and incorporated in the sheath, dilator, or needlehaving a more flexible distal section compared to the proximal tubebody. When tension is placed on the pull-wire, the sheath, dilator, orneedle is deflected into a curve. This helps direct the delivery systemto the target vessel location. The pullwire may be wound, crimped, spotwelded and/or soldered to the flat spring or collar placed in the sheathor dilator. This provides a stable point within the sheath or dilatorsfor the pullwire to exert tensile force thus steer the sheath ordilator. To incorporate steering in the needle, the pullwire may be spotwelded or soldered to one side of the needle hypotubing. The proximaltube body of the sheath or dilator may be reinforced by incorporating ahelically wound wire within the tubing extrusion to provide columnsupport from which to better deflect the distal section.

[0139] To perform an end-side anastomosis in accordance with theinvention, a delivery system, previously described, may be used toinsert the fitting partially into the vessel through a small puncture inthe vessel wall. As shown in FIG. 30, one end-side embodimentincorporates a retaining ring 254 similar to ring 140 or 143 having awide cross-section designed to mate with the distal end of the fittingafter being advanced over the fitting. The diameter of the retainingring is enlarged with an expanding tool (e.g. tool 108 or 160) while thefitting is slightly retracted. With the vessel snuggly around the distalend of a fitting 60, the retaining ring is released securing the vesselwall at the distal end of the fitting. Fittings such as that shown inFIG. 30 may incorporate a notch 56 near the distal end to help hold thevessel wall around the fitting while retracting the fitting andpositioning the retaining ring. This attachment methodology inherentlyplaces the distal end of the fitting flush with the side of the vesselto help prevent disrupting fluid flow through the host vessel,especially at the attachment site of the fitting. The retaining ring maybe further secured by placing a suture 80 through eyelets 100 and tyingthe ends of the retaining ring closed.

[0140]FIG. 30 shows a fitting 256 with barbs 257 to prevent axialmovement of the bypass graft 22 relative to the fitting. Alternatively,as shown in FIG. 18, notches may be fabricated in the fitting. The barbsor notches reinforce the compression fit between the bypass graft 22 andthe fitting, achieved by positioning retaining rings in the indentsdefined by the barbs or notches.

[0141] Another end-side fitting embodiment attaches an everted bypassgraft to a vessel wall 38. Bypass graft 22 is everted around the distalend of fitting 60 as previously described; the bypass graft is thensecured to the fitting using a retaining ring. The bypass graft andfitting are partially inserted through vessel wall 38 using thedeployment system described above. The bypass graft and fittingcombination is retracted thereby pulling the vessel wall located aroundthe fitting, proximal. A second retaining ring is opened by enlargingits diameter with an expanding tool and advanced over the section of thevessel wall contacting the fitting. The retaining ring is releasedclosing around the vessel wall and fitting. The retaining ring ispositioned such that it resides in the notched area of the fitting toprevent axial motion as discussed above. A secondary bond may be createdbetween the vessel wall and the fitting by placing a retaining ring 136(FIGS. 12a and b) around the distal flared end of the fitting.Alternatively, suture may be used to further secure the vessel wall tothe fitting by wrapping the suture around the vessel wall and fittingdistal to the retaining rings. As shown in FIGS. 33a and b, a retainingring 258 may alternatively include extensions 260 with holes 262. Theoperator can suture or staple this retaining ring to a tissue surfaceoutside the vessel providing an anchor between the retaining ring andthe host vessel.

[0142] An embodiment for producing an end-side anastomosis especiallydesigned for large diameter vessels (e.g. the aorta) is shown in FIG.31. After the bypass graft 22 and fitting 264 are inserted partiallythrough the vessel wall, a self-locking component 266 is advanced overteeth 268 incorporated in the fitting. A ratcheting mechanism 270prevents the self-locking component from dislodging from the fitting.The distal end 272 of the self-locking component is designed to match aflared end 274 of the fitting. Therefore, as the self-locking componentis further advanced relative to the fitting, the vessel wall becomescompressed between the self-locking component and the flared end of thefitting to produce a fluid tight, secure bond. This embodiment iscapable of bonding the vessel wall to bypass graft 22 and fitting 264after the bypass graft has been everted around the fitting.

[0143] An adaptation of the end-side fitting above, shown in FIGS. 32aand b, uses a flange 276 to secure the vessel wall to the bypass graft.A fitting 278 having a distal flared end is inserted through a punctureinto the vessel. Flange 276 mates with the distal, flared end of thefitting, is advanced over the fitting and is secured by suturing orstapling the flange to a tissue surface 280. In this position, thevessel wall is compressed between the fitting and the flange providing afluid tight seal between the bypass graft and the host vessel. As shownin FIG. 32c, fitting 278 and flange 276 can orient the bypass graft atselected angles relative to the host vessel. An alternative flange 282,shown in FIGS. 34a to d, is inserted into the interior of the vessel andis attached to the vessel wall. The flange contains holes 284 enablingthe operator to suture or staple the flange to the vessel wall. Theoperator locates the holes relative to the puncture site through thevessel wall, advances a needle through the holes and back outside thevessel wall where the suture is tied thereby attaching the flange to thevessel wall. FIG. 35 shows a clip to 286 that can be used to secureflange 276 in lieu of a suture or staples.

[0144]FIGS. 36a to e show an additional embodiment for producing anend-side anastomosis that compresses the vessel wall between two fittingcomponents. A fitting 288 incorporates a flared distal region 290 havinga slot 292 that defines two edges. The slotted distal end of the fittingis inserted through a puncture 294 of the vessel wall by positioning theedge of the slotted fitting at the puncture site, angling the distalflared region so the edge may be further advanced through the vesselwall, and rotating the fitting. Upon sufficient rotation of the fitting,the entire flared region of the fitting is advanced into the interior ofvessel 29, as shown in FIG. 36d. Then a compression ring 296 ispositioned over the fitting and past tabs 298 thereby compressing thevessel wall between flared distal end 290 and compression ring 296, asshown in FIG. 36e. For some applications, a conductive lead 300 isattached to fitting 288.

[0145] An adaptation of the screw-in fitting embodiment above is shownin FIGS. 37a to c. Here an edge 302 of flared end 290, separated by aslot, overlap to ensure a fluid tight fit in the slotted region afterdeploying the fitting and securing it to the vessel with a compressionring (not shown). As shown in FIG. 37c, the lower edge is advancedthrough the puncture site 294, and fitting 304 is rotated to advance thedistal, flared end of the fitting into the vessel. Once in the vessel, acompression ring is advanced over the fitting and is locked in placewith tabs 298 thereby securing the vessel wall between the distal,flared end of the fitting and the compression ring. The edges for thisfitting embodiment are biased to define a slot and facilitate rotationthrough the vessel wall, and overlap such that they contact enhancingthe leak resistance after the compression ring has been used to securethe fitting to the vessel wall. Fitting 304 includes multiple rows oftabs 298 to accommodate various sized vessel walls; this feature isimportant when treating vascular diseases associated with thickening ofthe vessel wall.

[0146] An alternative embodiment screw-in fitting 305 is shown in FIGS.37d and e. In this configuration, a guidewire is inserted through thevessel wall and into the interior of the host vessel by puncturing thevessel wall with a needle and inserting the guidewire through the lumenof the needle; the needle is removed from around the guidewire afterinserting the guidewire through the vessel wall. An insertion tubing 306containing a central lumen 308 follows the periphery of the flared end310 and is adapted to pass a guidewire. The guidewire is fed through theinsertion tubing to facilitate screwing the fitting past the vesselwall. The insertion tubing extends approximately 40% to 80% around theflared end circumference. Alternatively, the insertion tubing may beconfigured in sections extending around the circumference of the flaredend so the physician may determine how far around the flared end theguidewire must extend to rotate the flared end past the host vesselwall. A slot 312 through the distal flared end is adapted to accept thethickness of the vessel wall and enables screwing the fitting throughthe vessel wall. As the screw-in fitting is advanced over the guidewireand rotated, the fitting simultaneously expands the puncture throughvessel wall and inserts more of the distal flared end into the vesselinterior. Once the flared end of the fitting is inserted into the hostvessel interior, the guidewire is removed and the fitting is secured tothe vessel wall using a compression ring as described above, applyingadhesives to the bond, suturing the fitting, or other bonding process.

[0147] An alternative embodiment for performing an end-side anastomosisis shown in FIGS. 38a and b. The embodiment shown in FIGS. 38a and bincludes a fitting 314 with a bypass graft 22 everted over the distalend of the fitting. A retaining housing 316 is used to secure the bypassgraft to the fitting. This retaining housing permits radial expansionduring placement over the bypass graft and fitting, yet has a preshapedmemory to compress around the bypass graft and fitting thereby securingthe bypass graft to the fitting. This retaining housing has petals 318at its distal end, which compress into a low profile during deliverythrough a sheath and expand radially once deployed inside vessel 29. Thepetals extend at an angle between 30 and 150 degrees from the axis ofthe retaining housing. Petals 318 can extend at an angle larger than 90degrees from the retaining housing axis to increase the force exerted bythe petals against the vessel wall when the retaining housing isretracted against the host vessel wall.

[0148] The number of petals 318 incorporated in the retaining housingdesign depends on the size of the bypass graft and the size of the hostvessel. In this illustrated embodiment, eight petals are used. Afteradvancing the fitting through a sheath and past the vessel wall, thefitting is advanced beyond the end of the sheath and is no longerconstrained by the sheath, thus expands towards its restingconfiguration. Then the bypass graft and fitting combination is gentlyretracted to engage the interior vessel wall with the petals. Formechanical securing, a compression ring 320 is advanced over the fittingthereby compressing vessel wall 38 between the petals of the retaininghousing and the compression ring.

[0149] As shown in FIG. 38a, the retaining housing may incorporatethreads 322 with which to screw the compression ring and secure thecompression ring relative to the retaining housing. The threads areoriented only along the sections of the retaining housing configured toengage the compression ring; the slotted regions enabling the retaininghousing to radially expand do not include threads. The compression ringis alternatively locked in place using a ratchet mechanism, adhesives,sutures, or other attachment means to secure the compression ring inplace. The compression ring for this embodiment incorporates twocomponents: 1) a distal, flexible o-ring or disk 324 designed to producea fluid tight seal and prevent damaging the vessel wall by excesscompression; 2) a proximal, more rigid locking ring 325 used to maintainthe position of the o-ring or disk relative to the vessel wall. Thelocking ring shown in FIG. 38a is designed to match the threadsincorporated in the retaining housing.

[0150]FIGS. 39a and b show another fitting 326 used to produce anend-side anastomosis. In this embodiment, the fitting incorporatespetals 328 that collapse into a low profile during delivery through asheath and extend radially outward once deployed into the vesselinterior. In this embodiment, bypass graft 22 is advanced over theoutside of fitting 326 and is secured using a retaining ring 328.Alternatively, the fitting is laminated between layers of bypass graftmaterial. A compression ring 330 is advanced over the fitting, afterdeploying the fitting into the interior of the vessel, and is used tocompress the vessel wall between the deployed petals of the fitting anda protrusion 332 on the fitting. This secures the fitting to the vesselwall. As shown in FIG. 39c, the fittings that incorporate petals and thecompression rings used to produce end-side anastomoses may be configuredto produce an angle (A) between bypass graft 22 and the interior of thehost vessel. Like petals 316, petals 328 of fitting 326 extend at anangle between 30 and 150 degrees from the axis of the fitting. The angleof the petals can be chosen to increase the force exerted by the petalsagainst the vessel wall when the fitting is secured using compressionring 330.

[0151]FIGS. 40a to g show an embodiment for producing end-sideanastomoses mostly targeting medium to small diameter vessels (e.g.peripheral vessels and coronary vessels). For circumstances where thebypass graft is everted around the fitting and secured using a retainingring, the petals are incorporated into the retaining ring design, asshown in FIGS. 15e and f; otherwise, the petals are incorporated intothe fitting design. The petals shown in this embodiment are incorporatedinto the fitting design. The fitting incorporates petals that secure abypass graft to medium and small diameter vessels. As shown in FIGS. 40aand b, four petals are collapsed into a low profile for insertionthrough a sheath 176 during deployment into the vessel. Once positioned,the sheath 40 is retracted or the fitting is advanced beyond the sheathenabling the petals to expand toward their resting shape. This fittingincludes two petals 334 designed to extend axially along the vessel andpreformed to contact the host vessel wall. The fitting also includes twoother petals 336 and 338 designed to extend radially around a portion ofthe vessel. The petals provide a structure to prevent the fitting frompulling out of the vessel, restrict rotation of the fitting relative tothe bypass graft, ensure the host vessel does not collapse or constrictat the anastomosis site, and provide a support to compress the vesselwall between fitting components. Petals 336 and 338 are configured toreturn to a closed configuration in their resting state, as shown inFIG. 40f. Alternatively, these petals are configured to expand beyondthe closed configuration in their resting state, as shown in FIG. 40e.The latter configuration helps the fitting petals exert radial force onthe host vessel to better support the fitting within the host vessel andkeep the host vessel open at the bond interface. These end-side fittingsmay alternatively include more than 4 petals. FIG. 40g shows an end-sidefitting having two axially oriented petals 334 and four radiallyoriented petals 336 and 338. The petals 336 and 338 on this end-sidefitting embodiment are configured to expand beyond the closedconfiguration in their resting state; alternatively, the petals may beconfigured to return to a closed configuration in their resting state.All fittings that produce end-side anastomoses may be configured toproduce an angle between the bypass graft 22 and the interior of thehost vessel, preferably from 30 to 90 degrees.

[0152]FIGS. 41a to f show an adaptation of the end-side fitting that maybe folded to insert through a sheath with a smaller diameter than thefitting. As shown in FIG. 41b, this foldable fitting 340 may befabricated from a sheet of metal material that has been chemicallyetched, EDM, or laser drilled into the pattern shown; othermanufacturing processes may alternatively be used. The opposite sides342 and 344 of the fitting match so they may be bonded together (e.g.spot welded, soldered, adhesively bonded, or other process) to form theexpanded cross-section shown in FIG. 41c. Alternatively, the fitting maybe fabricated from a tubular metal material using chemical etching, EDM,laser drilling, or other manufacturing process to form the desiredpattern.

[0153] As shown in FIG. 41a, petals 346 are preshaped to expand radiallyoutward once they have been deployed outside the introducing sheath. Inthis configuration the vessel wall can be compressed between the petalsof the fitting and a compression ring as described above. The fitting isalso designed to fold into a reduced diameter (shown in FIG. 41d) duringdeployment and expand toward its resting shape once positioned past thedistal end of the sheath. The fitting includes links 348 that arefabricated by reducing the thickness or width of the fitting materialand act as hinges for the fitting to fold into a low profile. Thefoldable fitting embodiment shown in FIGS. 41a to f is designed with 6sides connected with links 348 so two adjacent sides are able to foldinward thereby reducing the diameter for insertion through the deliverysystem. The foldable fitting may further be configured so two moreadjacent sides that are opposite to the initially folded sides are ableto fold inward and further decrease the profile for insertion throughthe delivery system. To provide a fitting with six sides including twoopposing pairs of adjacent sides that fold inward, the pairs of foldablesides are fabricated with a width less than the width of the othersides. This applies to a four-sided fitting as well. In general, thepair of adjacent sides that fold inward have smaller widths than theremaining sides.

[0154] Petals 346 are either extensions of the sides or are separatecomponents bonded to the sides through spot welding, thermal bonding, oradhesive bonding. The petals are pre-shaped to contact the vessel wall,depending on the application and size of the vessel. When petals areformed by extending and pre-shaping the sides, more than one side can belinked to form a single petal. This feature is especially useful as thenumber of sides increases to facilitate folding the fitting. The sidesmay be linked during production of the fitting by chemical etching, EDM,or laser drilling. Alternatively, the sides may be spot welded orsoldered together to form links. The links of the petals can also permitfolding to facilitate folding of the entire fitting for insertionthrough a small diameter sheath. All end-side embodiments can bemodified to fold into a reduced diameter.

[0155] In the embodiment illustrated in FIGS. 41e and f, the foldablefitting incorporates a synthetic graft material 350 extruded, injectionmolded, or dipped onto fitting 340. These manufacturing processes causethe graft material to fill slots and holes 352 cut in the fitting. Thisproduces a more reliable bond between the synthetic graft material andthe expandable, foldable fitting. The covered fitting will still be ableto expand and fold as long as synthetic graft materials having a highpercent elongation characteristic are chosen. That way, the graftmaterial may stretch along the folds incorporated in the fitting. Abiological bypass graft (e.g. harvested vessel) may be sutured to theholes incorporated in the fitting, whether or not the fitting includes asynthetic graft material. The manufacturing processes and materials forfabricating this foldable end-side fitting may also be used to fabricateend-end fittings by excluding the petals from the design. In addition,the foldable fittings may extend throughout the length of the bypassgraft and be configured to maintain the potential to fold into a reduceddiameter.

[0156] The foldable fitting 353 may have more than 6 sides and beconfigured so multiple adjacent sides fold inward to further reduce theprofile for introduction, as shown in FIGS. 41g and h. Foldable fitting353 includes twelve sides interconnected with links. When the fittingincludes more than six sides, multiple pairs of adjacent sides can befolded inward without varying the widths of the sides. This furtherreduces the folded diameter of the fitting because pairs of adjacentsides folding inward do not interfere with the folding of opposite pairsof adjacent sides. The foldable fitting shown in FIGS. 41g and h alsopresent another adaptation to the foldable fitting, axial flexibility.By breaking the sides into more than one longitudinal section andconnecting the sections with slanted links 354, the fitting may still befolded along the links 822 and 826 but increases flexibility along thefitting axis. This feature is especially useful when the fittingstructure extends the length of the bypass graft where axial flexibilityis important to the deployment of the bypass graft and conformance tothe vasculature.

[0157]FIGS. 42, 43a, and 43 b show an end-end fitting that permitsretrograde blood flow through the anastomosis site. The fitting 356 hasholes 358 through the angled sections of the fittings to preserve fluidflow through the vessel distal and/or proximal, depending on thelocation of the fitting within the host vessel. For example, FIG. 42shows a bypass graft and fitting system 360 which, after deployed withinand attached to the vessel, maintains blood flow through the stenosis aswell as establishes a passage around the lesion 362. In addition,end-end fitting 356 maintains blood flow to branching vessels proximalto the anastomosis site.

[0158] As shown in FIGS. 43a and b, fittings 356 are attached to thevessel at two locations. The fitting is placed within the vessel andcontacts the interior surface of the vessel along a substantial length.FIG. 43b shows that the fitting may incorporate barbs 364 to preventaxial dislodgment of the fitting from the host vessel. These barbs mayalso provide a support to secure a retaining ring or suture tomechanically secure the fitting to the host vessel. The secondattachment location is at the insertion site through the vessel wall. Acompression ring or retaining ring 366 may be used to compress thevessel wall around the fitting and prevent fluid from leaking at theinsertion site. This fitting is particularly useful for medium diametervessels (>3 mm) where synthetic bypass grafts are used to supplement theblood flow through the vessel or shunt the blood flow to other vesselsor organs.

[0159]FIGS. 43c to g show additional end-end fitting embodiments thatpermit retrograde blood flow. A fitting 367 shown in FIGS. 43c and dincorporate a modification to the embodiment shown in FIGS. 43a and b inthat a short proximal extension 368 contacts the vessel wall along theinsertion site into the host vessel. This provides a structure to attacha compression ring and produce a fluid tight bond at the insertion site.Of course, a locking mechanism is incorporated in the fitting design toenable securing a compression ring to the fitting.

[0160]FIGS. 43f and g show another end-end fitting 370 that permitsretrograde perfusion. This fitting incorporates distal and proximalextensions used to secure the fitting to the host vessel using retainingrings; alternatively the distal and proximal extensions provide supportto secure the fitting to the host vessel wall at the insertion siteusing a compression ring. This fitting also includes two separatelumens; one lumen 372 connects blood flow from the bypass graft 22 tothe host vessel, and the second lumen 374 connects blood flow betweenregions of the host vessel proximal to the anastomosis site and distalto the anastomosis site.

[0161] Other fittings used to produce end-end anastomoses do not permitretrograde blood flow. FIG. 18 shows two end-end fittings that areattached in-line along a vessel 29. The fittings are designed to supportthe bypass graft at the vessel wall insertion site and prevent the hostvessel from constricting the diameter of the bypass graft 22. Aspreviously described, bypass graft 22 may be advanced through the graftfitting and everted around the distal end of the fitting. A retainingring 34 is used to secure the bypass graft 22 to the fitting and ispositioned within the notched region 56 of the fitting. When the bypassgraft 22 does not need to be everted, such as when using syntheticbypass grafts, the bypass graft may be attached to the exterior of thefitting as shown in FIG. 18, or the fitting may be laminated betweenlayers of synthetic bypass graft material. In addition to securing thebypass graft, the fittings help maintain the patency of the bypass graftby preventing the bypass graft from collapsing at the insertion site.These end-end fittings are particularly useful when performing in-lineanastomoses along a vessel and around a vascular abnormality. They arealso useful to treat total occlusions when retrograde blood flow is notbeneficial.

[0162] Additional Graft Fitting Features

[0163] Additional features may be included in any of the fittingconfigurations described above. FIG. 44 shows a fitting 376 similar tothe disclosed configurations having a strain relief 378 just proximal tothe anastomosis. This strain relief provides additional support to thebypass graft 22 while preventing kinking, especially during themanipulations involved in inserting and attaching the opposite end ofthe bypass graft. In addition, the strain relief reduces the profile ofthe fitting, making it less traumatic during use.

[0164]FIGS. 45a to c show a “Y” fitting 380 that used to branch fluidflow distant from the anastomosis site. The bypass graft may be securedto the “Y” fittings 380 using retaining rings previously described.Additionally, the “Y” fitting 380 (shown in FIG. 45c) may include barbs382 to improve the bond between the bypass graft 22 and “Y” fitting. Aswith the modular fittings 48 previously described in FIG. 3, the “Y”fittings 380 may have a larger cross-sectional area at the source end(i.e. the end located at the inflow of fluid from a vessel) than at thebranches.

[0165] The tear-away sheaths may incorporate features to better maintainblood flow through the host vessel while the tear-away sheath ispositioned inside the lumen of the host vessel. FIG. 46a shows cut-outareas 384 oriented along the tear-away sheath 3 86 and distributedradially around the sheath that permit blood to flow through the cut-outareas in the sheath and past the distal lumen of the sheath. Alternativedistributions and geometries for the cut-out areas may be chosen basedon the application and insertion requirements for the bypass graft. FIG.46b shows a tear-away sheath incorporating an anchoring extension 388 atthe distal end of the sheath. The extension is designed to maintainaccess between the tear-away sheath and the host vessel when the sheathis positioned perpendicular to the host vessel, and temporarily anchorthe sheath against the vessel wall.

[0166] The length of the sheath should be limited to that required toaccess the interior of the host vessel while ensuring short bypassgrafts may be inserted past the distal end of the sheath, especiallywhen the bypass graft has been secured at the opposite end. To make thesheath suitable for less invasive access, a long side arm extension tothe sheath may be incorporated to support the sheath duringmanipulations. The side arm should define two separable sections thatpermit splitting and remotely tear the sheath into two sections toremove from around the bypass graft.

[0167]FIG. 47 shows an adaptation of a delivery system that combines thetear-away sheath and the dilating member into one component. A dilatingsheath 390 contains at least one groove, slit, or series of perforations392 that enables splitting the dilating sheath for removal from aroundthe bypass graft. The dilating sheath also contains a tapered distal end394 that is designed to follow a needle or guidewire through a puncturein the vessel wall and expand the puncture to facilitate inserting themain section of the dilating sheath into the vessel. The dilating sheathhas a central lumen (not shown) adapted to pass the bypass graft andfitting combination. A plunger is used to advance the bypass graft andfitting combination past the tapered end of the dilating sheath and intothe host vessel. As discussed for the tear-away sheath, the dilatingsheath contains a hub 396 and hemostatic valve that permit splittingalong the at least one groove, slit, or series of perforations.

[0168] The tapered end of the dilating sheath must prevent collapsingwhile inserting through and opening the puncture site, and enableexpanding so the bypass graft and fitting combination may be advancedinto the host vessel lumen. The tapered end may be fabricated by cuttingthe end of the sheath tubing into three or more sections such that eachsection tapers distally, forming the sections such that they create asingle tapered distal end (the sections may overlap partially), andcovering the tapered distal end with a material having a low durometerand a large percent elongation (e.g. silicone and urethane). Thesections are formed such that they exert radial force to preventcollapsing while the dilating sheath is advanced through the puncturesite. The covering provides a fluid tight coating around the tapered endthat elongates as the sections are spread apart; this enables expandingthe diameter of the tapered end while the bypass graft and fittingcombination are inserted through the tapered end. An alternativefabrication process eliminates the need for the covering and bonds theoverlapping sections with an adhesive. The adhesive holds the positionof the tapered end sections and produces a fluid tight interface betweenthe sections but permits separating the sections as the plunger advancesthe bypass graft and fitting combination through the positioned dilatingsheath.

[0169] A further adaptation of the tapered end takes advantage ofmaterials having high water adsorption rates. Materials such ascellulose acetate are stiff when dehydrated and extremely flexible whenhydrated. The dilating sheath tubing may be fabricated from cellulosicsor similar material such that the tapered end is split into three ormore sections and formed into a taper. The dilating sheath is allowed todry where it is relatively stiff and exhibits sufficient column strengthto expand the puncture site. Once inside the vessel lumen, the tubingmaterial is exposed to fluid causing it to become more flexible. At thispoint, the tapered end may be separated into the three or more sectionsas the bypass graft and fitting combination are advanced into the hostvessel.

[0170]FIGS. 48a to d show an alternative to the snap fitting describedabove. The distal and proximal pieces are integrated into one component.This adaptation facilitates manipulation of the bypass graft relative tothe fitting since the operator only needs to hold the bypass graft and asingle fitting. Otherwise, the operator needs to hold the proximalpiece, distal piece, and bypass graft while securing the bypass graft tothe fitting. A distal piece 398 contains locking hinges 400 designed tomove axially along rails 402 incorporated in the proximal piece 404. Thelocking hinges move along the rails but are unable to be separated fromthe proximal piece. To accomplish this, the distal ends of the lockinghinges, positioned inside the rail openings, are larger than the widthof the rail openings. The distal ends of the locking hinges also haveextensions that mate and lock to teeth incorporated in the rails of thesnap fitting. During operation, the bypass graft is inserted through thelumen of proximal piece 404 and is advanced over the tapered end ofdistal piece 398. Then, the proximal piece is moved along the lockinghinges of the distal piece compressing the bypass graft between theproximal piece and distal piece. The ends of the locking hinges aresecured to the mating teeth of the rails to secure the distal piecerelative to the proximal piece. The distal piece as shown is configuredfor end-end anastomoses. However, it can be modified with featuresdescribed below to accommodate end-side anastomoses. This snap fittingcan be configured to evert the bypass graft, by modifying the fittingsuch that distal piece 398 can be advanced over proximal piece 404 andcompress the bypass graft between the distal piece and proximal piece.The bypass graft is advanced a sufficient amount through the innersurface of the proximal piece and is positioned over the outer surfaceof the distal piece. When the distal piece is advanced over the proximalpiece, the bypass graft is everted over the end of the proximal pieceand compressed between the distal and proximal pieces.

[0171]FIGS. 49a to d show an alternative snap fitting 406 that has acentral piece 408 and a lockable outer pieces 410 and 412. The outerpieces form a single cylindrical component or two distinct sections thatare designed to pivot about a hinge 414. The hinge connects the centralpiece and the outer pieces to facilitate manipulating the snap fittingand the bypass graft. The bypass graft is fed over the central piecefrom the side of the snap fitting not containing the hinge. The hinge islocated on one side of the central piece to facilitate advancing thebypass graft over the central piece without having to cut an incisionthrough the distal end of the bypass graft. After the bypass graft hasbeen positioned over the central piece, the outer piece is closedtogether compressing the bypass graft between the outer piece and thecentral piece. A locking mechanism is designed at the contacting ends ofthe outer pieces and is configured to bond the outer pieces in a closed,cylindrical position to reliably secure the bypass graft to the snapfitting. This may be achieved by incorporating mating teeth on oppositeends of the outer piece tailored to interlock when the ends overlap. Asshown in FIGS. 50a and b, this snap fitting may incorporate petals 416or other suitable modification (not shown but described below) so thefitting may be used to produce end-side anastomoses. Snap fitting 406can be used to secure the bypass graft in an everted orientation. Thebypass graft is inserted through the inner surface of central piece 408and is everted around the end of the central piece. With the bypassgraft everted around the central piece and located on the outer surfaceof the central piece, outer pieces 410 and 412 are locked, compressingthe everted graft against the central piece.

[0172] With the embodiments of the invention described above, the bypassgraft may be bonded to the fittings prior to securing the fittings tothe host vessel. As a result, this step may be performed outside thepatient enabling the physician to ensure a strong and leak resistantbond. Another advantage of the fitting embodiments described above arethat they may be configured to only or mostly expose the endotheliallayer 62 of a biological bypass graft to blood flow. This preventsthrombosis and other interactions observed between foreign materials andblood.

[0173]FIGS. 51a to d show a compression tool 420 designed to advance acompression ring over an end-side fitting without pulling the fittingout of the host vessel or damaging the fitting or host vessel during thesecuring process. FIGS. 51a and b show the compression tool in therelaxed position. The compression tool has a front handle piece 422 anda rear handle piece 424 spread apart in the relaxed position. The handlepieces are squeezed together to advance the compression ring over theend-side fitting as shown in FIGS. 51c and d. The compression tool maybe spring loaded to return to the relaxed position when the forcecausing the handle pieces to squeeze together is removed. Thecompression tool has a slot 426 through the distal section adapted tofit over the side of the bypass graft and fitting. This eliminates theneed to preload the bypass graft through the compression tool prior tothe procedure, and facilitates removing the compression tool aftersecuring the bypass graft to the host vessel. As shown in FIG. 51b, thecompression tool incorporates a slide 428 adapted to move along graspinglegs 430. The grasping legs are anchored to the rear handle piece andthe slide is advanced by squeezing the front handle piece towards therear handle piece. The slide and the grasping legs are configured todefine the slot 426 through the distal section of the compression tool.The grasping legs 430 are flared outward as they extend distally to fitaround the proximal end of the fitting in the relaxed state and closearound the fitting (shown in FIG. 51d) as the slide is advanced over thegrasping legs.

[0174] Slide extensions 432 are either incorporated in the distal end ofthe slide design or are bonded to the slide, depending on themanufacturing process and whether the slide extensions are fabricatedfrom the same material as the slide. The slide extensions exert a radialspring force to close the grasping legs around the fitting, and push thecompression ring over the end-side fitting. The compression ring isplaced over the grasping legs and against the slide extensions prior toadvancing the compression ring over the fitting. Then, the compressiontool is positioned so the grasping legs extend over the proximal end ofthe end-side fitting. The front handle piece is squeezed toward the rearhandle piece causing the slide 428 to advance over the grasping legs.Simultaneously, the grasping legs close around the fitting temporarilysecuring the compression tool to the fitting, and the compression ringis advanced over the fitting. This compression tool provides an anchorfor grabbing the proximal end of the fitting and advancing thecompression ring. This facilitates compressing the vessel wall betweenthe petals of the fitting inside the vessel and the compression ringoutside the vessel.

[0175] End-side fittings may be oval in cross-section as shown at 434 inFIGS. 52a and b. This facilitates an end-side anastomosis between alarge diameter bypass graft and a small diameter host vessel. Whensaphenous veins are harvested, they contained valves directing bloodflow towards the heart. The diameter of the saphenous vein increases inthe direction along the blood flow path. Instead of removing the valvesand damaging the vein, the saphenous vein can be oriented such that thevalves direct blood flow from the aorta to the coronary arteries duringa coronary artery bypass grafting procedure. Thus, the larger diametersection of the saphenous vein is located at the coronary artery and thesmaller diameter section of the saphenous vein is located at the aorta.The fittings can account for this by making the geometry of the evertedsaphenous vein oval to facilitate inserting an elongated fitting throughthe delivery sheath. The sheath cross-section also can be oval.Alternatively, the end-side fitting may include a central slot 436 asshown in FIGS. 52c and d. The central slot permits compressing thefitting into a low profile for insertion through a smaller diametersheath. When the fitting is advanced beyond the sheath, it expandstoward its oval configuration.

[0176]FIGS. 53a and b show a temporary graft 438 that can maintain bloodflow between two vessel ends for a short time before a permanent end-endanastomosis. The temporary graft has two end-end fittings 440 connectedwith a short length of graft material. The graft material may be apolymer, silicone, or metal. Graft 440 is fabricated from a hypotube(stainless steel or nickel titanium) in which longitudinal slots 442 inthe ends form the opposite end-end fittings. The ends of the fittingsare flared outward and treated to impose a memory elasticcharacteristic. Thus, the fittings are compressible into a low profilefor insertion into a vessel, and return towards an expanded restingconfiguration when an external compressing force is removed. A slidableor splittable tubing (not shown) can be used to provide the compressiveforce. In addition, the hockey stick device described above can be useto insert the end-end fittings into the host vessel ends. After graft438 is positioned, retaining rings 34 are advanced over the end-endfittings to compress the vessel wall against the fittings and thustemporarily secure the graft to the host vessel. The retaining rings areremovable from around the fittings when the physician is ready toperform the permanent anastomosis. Then, previously described fittingsand securing modalities are put to use. Temporary graft 438 rapidlyprovides blood flow between severed vessels or vessel ends duringtransplantations, when it is important to minimize ischemia time.

[0177] The fittings can be fabricated with holes, notches, and slots cutin the fitting, using laser drilling, EDM, milling, or othermanufacturing processes. The fittings also can be covered with a porousmaterial, such as collagen, fibrinogen, gelatin, and urethane, tofurther define a structure incorporating holes, notches, and slots. Theholes, notches and slots encourage neointimal cell growth to decreasebiological interactions of the portion of the fitting exposed to blood.

[0178] The fittings in accordance with this invention may be used in anycombination to secure bypass grafts at discrete vessel locations. Inaddition, synthetic and biological bypass grafts may also be used in anycombination with the graft fittings to produce passages around vascularabnormalities during a particular procedure.

We claim:
 1. An anastomosis connector system for providing support to abypass graft having a wall comprising: a fitting adapted for insertionat least partially through a vessel wall at an attachment site, thefitting being attachable to a distal end of the bypass graft; and anelongate member having a proximal end and a distal end with a lengththerebetween, wherein the member extends at least partially about thebypass graft at a location along the graft proximal to the attachmentsite between the distal end of the graft and the vessel wall such thatkinking is inhibited within the graft.
 2. The system of claim 1 whereinthe elongate member comprises a wire.
 3. The system of claim 1 whereinthe elongate member is wound into a helical pattern about the bypassgraft.
 4. The system of claim 1 wherein the elongate member is furtheradapted to increase a burst strength of the bypass graft.
 5. The systemof claim 1 wherein the elongate member is incorporated into the wall ofthe bypass graft.
 6. The system of claim 5 wherein the bypass graftcomprises a synthetic material.
 7. The system of claim 1 wherein theelongate member is adapted to be disposed exteriorly to the bypassgraft.
 8. The system of claim 1 wherein each of the proximal and distalends of the elongate member are bonded to the fitting.
 9. The system ofclaim 1 wherein the elongate member is integrally attached to thefitting.
 10. The system of claim 1 wherein the elongate member extendingabout the graft is adapted to orient the graft at an angle relative to alongitudinal axis defined along the vessel wall.
 11. The system of claim1 wherein the fitting comprises a material selected from the groupconsisting of stainless steel, titanium, nickel-titanium alloy,thermoplastic, thermoset plastic, silicone, and combinations thereof.12. The system of claim 1 wherein the elongate member comprises amaterial selected from the group consisting of stainless steel, shapememory alloy, and polymer.
 13. The system of claim 12 wherein the shapememory alloy comprises nickel titanium.
 14. The system of claim 12wherein the polymer comprises nylon or polyester.